diff --git a/README.md b/README.md
index c4806bf..e136558 100644
--- a/README.md
+++ b/README.md
@@ -33,8 +33,8 @@ func main() {
 	src := bytes.NewBufferString(`<? echo "Hello world";`)
 	nodes, comments, positions := parser.Parse(src, "example.php")
 
-	dumper := visitor.Dumper{"", comments, positions}
-	nodes.Walk(dumper)
+	visitor := Dumper{"", comments, positions}
+	nodes.Walk(visitor)
 }
 
 ```
diff --git a/visitor/dumper.go b/dumper.go
similarity index 70%
rename from visitor/dumper.go
rename to dumper.go
index ebfbfee..da02e3b 100644
--- a/visitor/dumper.go
+++ b/dumper.go
@@ -1,15 +1,25 @@
-package visitor
+package main
 
 import (
 	"fmt"
 	"reflect"
 
+	"github.com/z7zmey/php-parser/node"
 	"github.com/z7zmey/php-parser/position"
 
 	"github.com/z7zmey/php-parser/comment"
-	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
+func isWalkerImplementsNodeInterface(w walker.Walker) bool {
+	switch w.(type) {
+	case node.Node:
+		return true
+	default:
+		return false
+	}
+}
+
 // Dumper prints ast hierarchy to stdout
 // Also prints comments and positions attached to nodes
 type Dumper struct {
@@ -19,7 +29,12 @@ type Dumper struct {
 }
 
 // EnterNode is invoked at every node in heirerchy
-func (d Dumper) EnterNode(n node.Node) bool {
+func (d Dumper) EnterNode(w walker.Walker) bool {
+	if !isWalkerImplementsNodeInterface(w) {
+		return false
+	}
+
+	n := w.(node.Node)
 
 	fmt.Printf("%v%v", d.Indent, reflect.TypeOf(n))
 	if p := d.Positions[n]; p != nil {
@@ -41,12 +56,12 @@ func (d Dumper) EnterNode(n node.Node) bool {
 }
 
 // GetChildrenVisitor is invoked at every node parameter that contains children nodes
-func (d Dumper) GetChildrenVisitor(key string) node.Visitor {
+func (d Dumper) GetChildrenVisitor(key string) walker.Visitor {
 	fmt.Printf("%v%q:\n", d.Indent+"  ", key)
 	return Dumper{d.Indent + "    ", d.Comments, d.Positions}
 }
 
 // LeaveNode is invoked after node process
-func (d Dumper) LeaveNode(n node.Node) {
+func (d Dumper) LeaveNode(n walker.Walker) {
 	// do nothing
 }
diff --git a/main.go b/main.go
index 6e8e63a..6a153c3 100644
--- a/main.go
+++ b/main.go
@@ -9,7 +9,6 @@ import (
 
 	"github.com/yookoala/realpath"
 	"github.com/z7zmey/php-parser/parser"
-	"github.com/z7zmey/php-parser/visitor"
 )
 
 func main() {
@@ -26,7 +25,7 @@ func main() {
 				src, _ := os.Open(string(path))
 				nodes, comments, positions := parser.Parse(src, path)
 
-				visitor := visitor.Dumper{
+				visitor := Dumper{
 					Indent:    "  | ",
 					Comments:  comments,
 					Positions: positions,
diff --git a/node/argument.go b/node/argument.go
index 7fae201..3f2c076 100644
--- a/node/argument.go
+++ b/node/argument.go
@@ -1,5 +1,7 @@
 package node
 
+import "github.com/z7zmey/php-parser/walker"
+
 // Argument node
 type Argument struct {
 	Variadic bool // if ... before variable
@@ -23,7 +25,7 @@ func (n *Argument) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Argument) Walk(v Visitor) {
+func (n *Argument) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/array.go b/node/expr/array.go
index d7ce07f..d671d82 100644
--- a/node/expr/array.go
+++ b/node/expr/array.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Array node
@@ -23,7 +24,7 @@ func (n *Array) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Array) Walk(v node.Visitor) {
+func (n *Array) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/array_dim_fetch.go b/node/expr/array_dim_fetch.go
index 25a95c0..e1043b4 100644
--- a/node/expr/array_dim_fetch.go
+++ b/node/expr/array_dim_fetch.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ArrayDimFetch node
@@ -25,7 +26,7 @@ func (n *ArrayDimFetch) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ArrayDimFetch) Walk(v node.Visitor) {
+func (n *ArrayDimFetch) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/array_item.go b/node/expr/array_item.go
index f2dfb51..321a867 100644
--- a/node/expr/array_item.go
+++ b/node/expr/array_item.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ArrayItem node
@@ -29,7 +30,7 @@ func (n *ArrayItem) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ArrayItem) Walk(v node.Visitor) {
+func (n *ArrayItem) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/assign.go b/node/expr/assign_op/assign.go
index 8e36d0d..8d467c3 100644
--- a/node/expr/assign_op/assign.go
+++ b/node/expr/assign_op/assign.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Assign node
@@ -26,7 +27,7 @@ func (n *Assign) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Assign) Walk(v node.Visitor) {
+func (n *Assign) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/assign_ref.go b/node/expr/assign_op/assign_ref.go
index f42c954..2f69169 100644
--- a/node/expr/assign_op/assign_ref.go
+++ b/node/expr/assign_op/assign_ref.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // AssignRef node
@@ -26,7 +27,7 @@ func (n *AssignRef) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *AssignRef) Walk(v node.Visitor) {
+func (n *AssignRef) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/bitwise_and.go b/node/expr/assign_op/bitwise_and.go
index af2d70c..c28a488 100644
--- a/node/expr/assign_op/bitwise_and.go
+++ b/node/expr/assign_op/bitwise_and.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BitwiseAnd node
@@ -26,7 +27,7 @@ func (n *BitwiseAnd) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BitwiseAnd) Walk(v node.Visitor) {
+func (n *BitwiseAnd) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/bitwise_or.go b/node/expr/assign_op/bitwise_or.go
index 60534cb..b5270db 100644
--- a/node/expr/assign_op/bitwise_or.go
+++ b/node/expr/assign_op/bitwise_or.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BitwiseOr node
@@ -26,7 +27,7 @@ func (n *BitwiseOr) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BitwiseOr) Walk(v node.Visitor) {
+func (n *BitwiseOr) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/bitwise_xor.go b/node/expr/assign_op/bitwise_xor.go
index f7f5cd1..402be35 100644
--- a/node/expr/assign_op/bitwise_xor.go
+++ b/node/expr/assign_op/bitwise_xor.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BitwiseXor node
@@ -26,7 +27,7 @@ func (n *BitwiseXor) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BitwiseXor) Walk(v node.Visitor) {
+func (n *BitwiseXor) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/concat.go b/node/expr/assign_op/concat.go
index 5ae02de..a27bebf 100644
--- a/node/expr/assign_op/concat.go
+++ b/node/expr/assign_op/concat.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Concat node
@@ -26,7 +27,7 @@ func (n *Concat) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Concat) Walk(v node.Visitor) {
+func (n *Concat) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/div.go b/node/expr/assign_op/div.go
index faa462e..049a029 100644
--- a/node/expr/assign_op/div.go
+++ b/node/expr/assign_op/div.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Div node
@@ -26,7 +27,7 @@ func (n *Div) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Div) Walk(v node.Visitor) {
+func (n *Div) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/minus.go b/node/expr/assign_op/minus.go
index 8734190..8da18e0 100644
--- a/node/expr/assign_op/minus.go
+++ b/node/expr/assign_op/minus.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Minus node
@@ -26,7 +27,7 @@ func (n *Minus) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Minus) Walk(v node.Visitor) {
+func (n *Minus) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/mod.go b/node/expr/assign_op/mod.go
index 031de8f..0c700cb 100644
--- a/node/expr/assign_op/mod.go
+++ b/node/expr/assign_op/mod.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Mod node
@@ -26,7 +27,7 @@ func (n *Mod) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Mod) Walk(v node.Visitor) {
+func (n *Mod) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/mul.go b/node/expr/assign_op/mul.go
index 046143e..33b1809 100644
--- a/node/expr/assign_op/mul.go
+++ b/node/expr/assign_op/mul.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Mul node
@@ -26,7 +27,7 @@ func (n *Mul) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Mul) Walk(v node.Visitor) {
+func (n *Mul) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/plus.go b/node/expr/assign_op/plus.go
index 3887630..d86e7fc 100644
--- a/node/expr/assign_op/plus.go
+++ b/node/expr/assign_op/plus.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Plus node
@@ -26,7 +27,7 @@ func (n *Plus) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Plus) Walk(v node.Visitor) {
+func (n *Plus) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/pow.go b/node/expr/assign_op/pow.go
index 6e89c60..3d34116 100644
--- a/node/expr/assign_op/pow.go
+++ b/node/expr/assign_op/pow.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Pow node
@@ -26,7 +27,7 @@ func (n *Pow) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Pow) Walk(v node.Visitor) {
+func (n *Pow) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/shift_left.go b/node/expr/assign_op/shift_left.go
index caf3149..c309685 100644
--- a/node/expr/assign_op/shift_left.go
+++ b/node/expr/assign_op/shift_left.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ShiftLeft node
@@ -26,7 +27,7 @@ func (n *ShiftLeft) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ShiftLeft) Walk(v node.Visitor) {
+func (n *ShiftLeft) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/assign_op/shift_right.go b/node/expr/assign_op/shift_right.go
index 39b0e00..85cc5be 100644
--- a/node/expr/assign_op/shift_right.go
+++ b/node/expr/assign_op/shift_right.go
@@ -2,6 +2,7 @@ package assign_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ShiftRight node
@@ -26,7 +27,7 @@ func (n *ShiftRight) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ShiftRight) Walk(v node.Visitor) {
+func (n *ShiftRight) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/bitwise_and.go b/node/expr/binary_op/bitwise_and.go
index 25bdad3..ce77975 100644
--- a/node/expr/binary_op/bitwise_and.go
+++ b/node/expr/binary_op/bitwise_and.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BitwiseAnd node
@@ -26,7 +27,7 @@ func (n *BitwiseAnd) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BitwiseAnd) Walk(v node.Visitor) {
+func (n *BitwiseAnd) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/bitwise_or.go b/node/expr/binary_op/bitwise_or.go
index 5114445..017769c 100644
--- a/node/expr/binary_op/bitwise_or.go
+++ b/node/expr/binary_op/bitwise_or.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BitwiseOr node
@@ -26,7 +27,7 @@ func (n *BitwiseOr) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BitwiseOr) Walk(v node.Visitor) {
+func (n *BitwiseOr) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/bitwise_xor.go b/node/expr/binary_op/bitwise_xor.go
index 6c0c18d..24d97f7 100644
--- a/node/expr/binary_op/bitwise_xor.go
+++ b/node/expr/binary_op/bitwise_xor.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BitwiseXor node
@@ -26,7 +27,7 @@ func (n *BitwiseXor) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BitwiseXor) Walk(v node.Visitor) {
+func (n *BitwiseXor) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/boolean_and.go b/node/expr/binary_op/boolean_and.go
index e50ef96..e6319c0 100644
--- a/node/expr/binary_op/boolean_and.go
+++ b/node/expr/binary_op/boolean_and.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BooleanAnd node
@@ -26,7 +27,7 @@ func (n *BooleanAnd) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BooleanAnd) Walk(v node.Visitor) {
+func (n *BooleanAnd) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/boolean_or.go b/node/expr/binary_op/boolean_or.go
index 2615558..e9b7e42 100644
--- a/node/expr/binary_op/boolean_or.go
+++ b/node/expr/binary_op/boolean_or.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BooleanOr node
@@ -26,7 +27,7 @@ func (n *BooleanOr) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BooleanOr) Walk(v node.Visitor) {
+func (n *BooleanOr) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/coalesce.go b/node/expr/binary_op/coalesce.go
index 82d48fa..0efd847 100644
--- a/node/expr/binary_op/coalesce.go
+++ b/node/expr/binary_op/coalesce.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Coalesce node
@@ -26,7 +27,7 @@ func (n *Coalesce) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Coalesce) Walk(v node.Visitor) {
+func (n *Coalesce) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/concat.go b/node/expr/binary_op/concat.go
index 5ee11d5..19c1b85 100644
--- a/node/expr/binary_op/concat.go
+++ b/node/expr/binary_op/concat.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Concat node
@@ -26,7 +27,7 @@ func (n *Concat) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Concat) Walk(v node.Visitor) {
+func (n *Concat) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/div.go b/node/expr/binary_op/div.go
index 155047c..c2c5f17 100644
--- a/node/expr/binary_op/div.go
+++ b/node/expr/binary_op/div.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Div node
@@ -26,7 +27,7 @@ func (n *Div) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Div) Walk(v node.Visitor) {
+func (n *Div) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/equal.go b/node/expr/binary_op/equal.go
index 931aa32..a17d019 100644
--- a/node/expr/binary_op/equal.go
+++ b/node/expr/binary_op/equal.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Equal node
@@ -26,7 +27,7 @@ func (n *Equal) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Equal) Walk(v node.Visitor) {
+func (n *Equal) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/greater.go b/node/expr/binary_op/greater.go
index 558b3f7..58e161d 100644
--- a/node/expr/binary_op/greater.go
+++ b/node/expr/binary_op/greater.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Greater node
@@ -26,7 +27,7 @@ func (n *Greater) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Greater) Walk(v node.Visitor) {
+func (n *Greater) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/greater_or_equal.go b/node/expr/binary_op/greater_or_equal.go
index b378e91..d3e5e6f 100644
--- a/node/expr/binary_op/greater_or_equal.go
+++ b/node/expr/binary_op/greater_or_equal.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // GreaterOrEqual node
@@ -26,7 +27,7 @@ func (n *GreaterOrEqual) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *GreaterOrEqual) Walk(v node.Visitor) {
+func (n *GreaterOrEqual) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/identical.go b/node/expr/binary_op/identical.go
index 2763822..273af66 100644
--- a/node/expr/binary_op/identical.go
+++ b/node/expr/binary_op/identical.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Identical node
@@ -26,7 +27,7 @@ func (n *Identical) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Identical) Walk(v node.Visitor) {
+func (n *Identical) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/logical_and.go b/node/expr/binary_op/logical_and.go
index 17790eb..2469424 100644
--- a/node/expr/binary_op/logical_and.go
+++ b/node/expr/binary_op/logical_and.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // LogicalAnd node
@@ -26,7 +27,7 @@ func (n *LogicalAnd) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *LogicalAnd) Walk(v node.Visitor) {
+func (n *LogicalAnd) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/logical_or.go b/node/expr/binary_op/logical_or.go
index 341198f..894f926 100644
--- a/node/expr/binary_op/logical_or.go
+++ b/node/expr/binary_op/logical_or.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // LogicalOr node
@@ -26,7 +27,7 @@ func (n *LogicalOr) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *LogicalOr) Walk(v node.Visitor) {
+func (n *LogicalOr) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/logical_xor.go b/node/expr/binary_op/logical_xor.go
index 4f1db5d..97b3e41 100644
--- a/node/expr/binary_op/logical_xor.go
+++ b/node/expr/binary_op/logical_xor.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // LogicalXor node
@@ -26,7 +27,7 @@ func (n *LogicalXor) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *LogicalXor) Walk(v node.Visitor) {
+func (n *LogicalXor) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/minus.go b/node/expr/binary_op/minus.go
index ddaba52..ee8057b 100644
--- a/node/expr/binary_op/minus.go
+++ b/node/expr/binary_op/minus.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Minus node
@@ -26,7 +27,7 @@ func (n *Minus) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Minus) Walk(v node.Visitor) {
+func (n *Minus) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/mod.go b/node/expr/binary_op/mod.go
index 39a1e5f..81975fe 100644
--- a/node/expr/binary_op/mod.go
+++ b/node/expr/binary_op/mod.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Mod node
@@ -26,7 +27,7 @@ func (n *Mod) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Mod) Walk(v node.Visitor) {
+func (n *Mod) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/mul.go b/node/expr/binary_op/mul.go
index 15f6383..757d932 100644
--- a/node/expr/binary_op/mul.go
+++ b/node/expr/binary_op/mul.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Mul node
@@ -26,7 +27,7 @@ func (n *Mul) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Mul) Walk(v node.Visitor) {
+func (n *Mul) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/not_equal.go b/node/expr/binary_op/not_equal.go
index 2d8f7ad..224812b 100644
--- a/node/expr/binary_op/not_equal.go
+++ b/node/expr/binary_op/not_equal.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // NotEqual node
@@ -26,7 +27,7 @@ func (n *NotEqual) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *NotEqual) Walk(v node.Visitor) {
+func (n *NotEqual) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/not_identical.go b/node/expr/binary_op/not_identical.go
index 7fe87ee..e24e474 100644
--- a/node/expr/binary_op/not_identical.go
+++ b/node/expr/binary_op/not_identical.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // NotIdentical node
@@ -26,7 +27,7 @@ func (n *NotIdentical) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *NotIdentical) Walk(v node.Visitor) {
+func (n *NotIdentical) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/plus.go b/node/expr/binary_op/plus.go
index 60b9131..f8c8649 100644
--- a/node/expr/binary_op/plus.go
+++ b/node/expr/binary_op/plus.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Plus node
@@ -26,7 +27,7 @@ func (n *Plus) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Plus) Walk(v node.Visitor) {
+func (n *Plus) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/pow.go b/node/expr/binary_op/pow.go
index 352243b..170c740 100644
--- a/node/expr/binary_op/pow.go
+++ b/node/expr/binary_op/pow.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Pow node
@@ -26,7 +27,7 @@ func (n *Pow) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Pow) Walk(v node.Visitor) {
+func (n *Pow) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/shift_left.go b/node/expr/binary_op/shift_left.go
index 918d2ef..c1477ef 100644
--- a/node/expr/binary_op/shift_left.go
+++ b/node/expr/binary_op/shift_left.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ShiftLeft node
@@ -26,7 +27,7 @@ func (n *ShiftLeft) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ShiftLeft) Walk(v node.Visitor) {
+func (n *ShiftLeft) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/shift_right.go b/node/expr/binary_op/shift_right.go
index d8892a1..e8c9751 100644
--- a/node/expr/binary_op/shift_right.go
+++ b/node/expr/binary_op/shift_right.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ShiftRight node
@@ -26,7 +27,7 @@ func (n *ShiftRight) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ShiftRight) Walk(v node.Visitor) {
+func (n *ShiftRight) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/smaller.go b/node/expr/binary_op/smaller.go
index d2fce78..735c4a3 100644
--- a/node/expr/binary_op/smaller.go
+++ b/node/expr/binary_op/smaller.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Smaller node
@@ -26,7 +27,7 @@ func (n *Smaller) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Smaller) Walk(v node.Visitor) {
+func (n *Smaller) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/smaller_or_equal.go b/node/expr/binary_op/smaller_or_equal.go
index ab5905c..397fd71 100644
--- a/node/expr/binary_op/smaller_or_equal.go
+++ b/node/expr/binary_op/smaller_or_equal.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // SmallerOrEqual node
@@ -26,7 +27,7 @@ func (n *SmallerOrEqual) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *SmallerOrEqual) Walk(v node.Visitor) {
+func (n *SmallerOrEqual) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/binary_op/spaceship.go b/node/expr/binary_op/spaceship.go
index 4eb48e9..8eebbbf 100644
--- a/node/expr/binary_op/spaceship.go
+++ b/node/expr/binary_op/spaceship.go
@@ -2,6 +2,7 @@ package binary_op
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Spaceship node
@@ -26,7 +27,7 @@ func (n *Spaceship) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Spaceship) Walk(v node.Visitor) {
+func (n *Spaceship) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/bitwise_not.go b/node/expr/bitwise_not.go
index e90309f..41dcd47 100644
--- a/node/expr/bitwise_not.go
+++ b/node/expr/bitwise_not.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BitwiseNot node
@@ -23,7 +24,7 @@ func (n *BitwiseNot) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BitwiseNot) Walk(v node.Visitor) {
+func (n *BitwiseNot) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/boolean_not.go b/node/expr/boolean_not.go
index 09a6285..3bade30 100644
--- a/node/expr/boolean_not.go
+++ b/node/expr/boolean_not.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // BooleanNot node
@@ -23,7 +24,7 @@ func (n *BooleanNot) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *BooleanNot) Walk(v node.Visitor) {
+func (n *BooleanNot) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/cast/cast_array.go b/node/expr/cast/cast_array.go
index ccff06b..b8e0e57 100644
--- a/node/expr/cast/cast_array.go
+++ b/node/expr/cast/cast_array.go
@@ -2,6 +2,7 @@ package cast
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // CastArray node
@@ -25,7 +26,7 @@ func (n *CastArray) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *CastArray) Walk(v node.Visitor) {
+func (n *CastArray) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/cast/cast_bool.go b/node/expr/cast/cast_bool.go
index a7e1cda..06a3ece 100644
--- a/node/expr/cast/cast_bool.go
+++ b/node/expr/cast/cast_bool.go
@@ -2,6 +2,7 @@ package cast
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // CastBool node
@@ -25,7 +26,7 @@ func (n *CastBool) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *CastBool) Walk(v node.Visitor) {
+func (n *CastBool) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/cast/cast_double.go b/node/expr/cast/cast_double.go
index d76c72f..4c4ef4d 100644
--- a/node/expr/cast/cast_double.go
+++ b/node/expr/cast/cast_double.go
@@ -2,6 +2,7 @@ package cast
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // CastDouble node
@@ -25,7 +26,7 @@ func (n *CastDouble) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *CastDouble) Walk(v node.Visitor) {
+func (n *CastDouble) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/cast/cast_int.go b/node/expr/cast/cast_int.go
index 4372707..9d30bdc 100644
--- a/node/expr/cast/cast_int.go
+++ b/node/expr/cast/cast_int.go
@@ -2,6 +2,7 @@ package cast
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // CastInt node
@@ -25,7 +26,7 @@ func (n *CastInt) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *CastInt) Walk(v node.Visitor) {
+func (n *CastInt) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/cast/cast_object.go b/node/expr/cast/cast_object.go
index 6ba2a28..afbc0e3 100644
--- a/node/expr/cast/cast_object.go
+++ b/node/expr/cast/cast_object.go
@@ -2,6 +2,7 @@ package cast
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // CastObject node
@@ -25,7 +26,7 @@ func (n *CastObject) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *CastObject) Walk(v node.Visitor) {
+func (n *CastObject) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/cast/cast_string.go b/node/expr/cast/cast_string.go
index d40ef4d..65fa986 100644
--- a/node/expr/cast/cast_string.go
+++ b/node/expr/cast/cast_string.go
@@ -2,6 +2,7 @@ package cast
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // CastString node
@@ -25,7 +26,7 @@ func (n *CastString) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *CastString) Walk(v node.Visitor) {
+func (n *CastString) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/cast/cast_unset.go b/node/expr/cast/cast_unset.go
index 5a1028f..9f3180f 100644
--- a/node/expr/cast/cast_unset.go
+++ b/node/expr/cast/cast_unset.go
@@ -2,6 +2,7 @@ package cast
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // CastUnset node
@@ -25,7 +26,7 @@ func (n *CastUnset) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *CastUnset) Walk(v node.Visitor) {
+func (n *CastUnset) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/class_const_fetch.go b/node/expr/class_const_fetch.go
index 84ae0a4..2dac6f8 100644
--- a/node/expr/class_const_fetch.go
+++ b/node/expr/class_const_fetch.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ClassConstFetch node
@@ -25,7 +26,7 @@ func (n *ClassConstFetch) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ClassConstFetch) Walk(v node.Visitor) {
+func (n *ClassConstFetch) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/clone.go b/node/expr/clone.go
index 1313335..bae6b55 100644
--- a/node/expr/clone.go
+++ b/node/expr/clone.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Clone node
@@ -23,7 +24,7 @@ func (n *Clone) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Clone) Walk(v node.Visitor) {
+func (n *Clone) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/closure.go b/node/expr/closure.go
index b4a20de..39c9595 100644
--- a/node/expr/closure.go
+++ b/node/expr/closure.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Closure node
@@ -39,7 +40,7 @@ func (n *Closure) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Closure) Walk(v node.Visitor) {
+func (n *Closure) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/closure_use.go b/node/expr/closure_use.go
index 8be613c..2ba7191 100644
--- a/node/expr/closure_use.go
+++ b/node/expr/closure_use.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ClusureUse node
@@ -27,7 +28,7 @@ func (n *ClusureUse) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ClusureUse) Walk(v node.Visitor) {
+func (n *ClusureUse) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/const_fetch.go b/node/expr/const_fetch.go
index c8bcea9..ce22586 100644
--- a/node/expr/const_fetch.go
+++ b/node/expr/const_fetch.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ConstFetch node
@@ -23,7 +24,7 @@ func (n *ConstFetch) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ConstFetch) Walk(v node.Visitor) {
+func (n *ConstFetch) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/empty.go b/node/expr/empty.go
index 4fb986a..43cc005 100644
--- a/node/expr/empty.go
+++ b/node/expr/empty.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Empty node
@@ -23,7 +24,7 @@ func (n *Empty) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Empty) Walk(v node.Visitor) {
+func (n *Empty) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/error_suppress.go b/node/expr/error_suppress.go
index 26f5f8d..d3a1cb7 100644
--- a/node/expr/error_suppress.go
+++ b/node/expr/error_suppress.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ErrorSuppress node
@@ -23,7 +24,7 @@ func (n *ErrorSuppress) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ErrorSuppress) Walk(v node.Visitor) {
+func (n *ErrorSuppress) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/eval.go b/node/expr/eval.go
index dd7c37a..fed6f98 100644
--- a/node/expr/eval.go
+++ b/node/expr/eval.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Eval node
@@ -23,7 +24,7 @@ func (n *Eval) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Eval) Walk(v node.Visitor) {
+func (n *Eval) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/exit.go b/node/expr/exit.go
index 653ae93..f01fa0b 100644
--- a/node/expr/exit.go
+++ b/node/expr/exit.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Exit node
@@ -27,7 +28,7 @@ func (n *Exit) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Exit) Walk(v node.Visitor) {
+func (n *Exit) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/function_call.go b/node/expr/function_call.go
index d7fdfe3..a7f1be5 100644
--- a/node/expr/function_call.go
+++ b/node/expr/function_call.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // FunctionCall node
@@ -25,7 +26,7 @@ func (n *FunctionCall) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *FunctionCall) Walk(v node.Visitor) {
+func (n *FunctionCall) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/include.go b/node/expr/include.go
index c986a09..783f4b6 100644
--- a/node/expr/include.go
+++ b/node/expr/include.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Include node
@@ -23,7 +24,7 @@ func (n *Include) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Include) Walk(v node.Visitor) {
+func (n *Include) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/include_once.go b/node/expr/include_once.go
index 00b2d88..62ab326 100644
--- a/node/expr/include_once.go
+++ b/node/expr/include_once.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // IncludeOnce node
@@ -23,7 +24,7 @@ func (n *IncludeOnce) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *IncludeOnce) Walk(v node.Visitor) {
+func (n *IncludeOnce) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/instance_of.go b/node/expr/instance_of.go
index 27cb2a1..f4eac94 100644
--- a/node/expr/instance_of.go
+++ b/node/expr/instance_of.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // InstanceOf node
@@ -25,7 +26,7 @@ func (n *InstanceOf) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *InstanceOf) Walk(v node.Visitor) {
+func (n *InstanceOf) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/isset.go b/node/expr/isset.go
index 2efca83..f165ede 100644
--- a/node/expr/isset.go
+++ b/node/expr/isset.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Isset node
@@ -23,7 +24,7 @@ func (n *Isset) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Isset) Walk(v node.Visitor) {
+func (n *Isset) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/list.go b/node/expr/list.go
index f7e17c0..40dc55b 100644
--- a/node/expr/list.go
+++ b/node/expr/list.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // List node
@@ -23,7 +24,7 @@ func (n *List) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *List) Walk(v node.Visitor) {
+func (n *List) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/method_call.go b/node/expr/method_call.go
index 3bd8104..173bc1c 100644
--- a/node/expr/method_call.go
+++ b/node/expr/method_call.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // MethodCall node
@@ -27,7 +28,7 @@ func (n *MethodCall) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *MethodCall) Walk(v node.Visitor) {
+func (n *MethodCall) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/new.go b/node/expr/new.go
index 3c47b32..92b6eb9 100644
--- a/node/expr/new.go
+++ b/node/expr/new.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // New node
@@ -25,7 +26,7 @@ func (n *New) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *New) Walk(v node.Visitor) {
+func (n *New) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/post_dec.go b/node/expr/post_dec.go
index 478c496..bd3e024 100644
--- a/node/expr/post_dec.go
+++ b/node/expr/post_dec.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // PostDec node
@@ -23,7 +24,7 @@ func (n *PostDec) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *PostDec) Walk(v node.Visitor) {
+func (n *PostDec) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/post_inc.go b/node/expr/post_inc.go
index e6448c5..8f2ad5a 100644
--- a/node/expr/post_inc.go
+++ b/node/expr/post_inc.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // PostInc node
@@ -23,7 +24,7 @@ func (n *PostInc) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *PostInc) Walk(v node.Visitor) {
+func (n *PostInc) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/pre_dec.go b/node/expr/pre_dec.go
index 20bd7cf..3e89f21 100644
--- a/node/expr/pre_dec.go
+++ b/node/expr/pre_dec.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // PreDec node
@@ -23,7 +24,7 @@ func (n *PreDec) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *PreDec) Walk(v node.Visitor) {
+func (n *PreDec) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/pre_inc.go b/node/expr/pre_inc.go
index cea917d..6b9e89a 100644
--- a/node/expr/pre_inc.go
+++ b/node/expr/pre_inc.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // PreInc node
@@ -23,7 +24,7 @@ func (n *PreInc) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *PreInc) Walk(v node.Visitor) {
+func (n *PreInc) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/print.go b/node/expr/print.go
index 0649f7f..ab5553f 100644
--- a/node/expr/print.go
+++ b/node/expr/print.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Print node
@@ -23,7 +24,7 @@ func (n *Print) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Print) Walk(v node.Visitor) {
+func (n *Print) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/property_fetch.go b/node/expr/property_fetch.go
index f23984a..16db548 100644
--- a/node/expr/property_fetch.go
+++ b/node/expr/property_fetch.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // PropertyFetch node
@@ -25,7 +26,7 @@ func (n *PropertyFetch) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *PropertyFetch) Walk(v node.Visitor) {
+func (n *PropertyFetch) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/require.go b/node/expr/require.go
index 105b12e..03acd8f 100644
--- a/node/expr/require.go
+++ b/node/expr/require.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Require node
@@ -23,7 +24,7 @@ func (n *Require) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Require) Walk(v node.Visitor) {
+func (n *Require) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/require_once.go b/node/expr/require_once.go
index ef409b0..18205e9 100644
--- a/node/expr/require_once.go
+++ b/node/expr/require_once.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // RequireOnce node
@@ -23,7 +24,7 @@ func (n *RequireOnce) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *RequireOnce) Walk(v node.Visitor) {
+func (n *RequireOnce) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/shell_exec.go b/node/expr/shell_exec.go
index fc0913e..c6efbfb 100644
--- a/node/expr/shell_exec.go
+++ b/node/expr/shell_exec.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ShellExec node
@@ -23,7 +24,7 @@ func (n *ShellExec) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ShellExec) Walk(v node.Visitor) {
+func (n *ShellExec) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/short_array.go b/node/expr/short_array.go
index 55dfe08..09c9d31 100644
--- a/node/expr/short_array.go
+++ b/node/expr/short_array.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ShortArray node
@@ -23,7 +24,7 @@ func (n *ShortArray) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ShortArray) Walk(v node.Visitor) {
+func (n *ShortArray) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/short_list.go b/node/expr/short_list.go
index 0da0823..9a2a1f6 100644
--- a/node/expr/short_list.go
+++ b/node/expr/short_list.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ShortList node
@@ -23,7 +24,7 @@ func (n *ShortList) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ShortList) Walk(v node.Visitor) {
+func (n *ShortList) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/static_call.go b/node/expr/static_call.go
index fa50a7a..63cd6b4 100644
--- a/node/expr/static_call.go
+++ b/node/expr/static_call.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // StaticCall node
@@ -27,7 +28,7 @@ func (n *StaticCall) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *StaticCall) Walk(v node.Visitor) {
+func (n *StaticCall) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/static_property_fetch.go b/node/expr/static_property_fetch.go
index 9dfcd0f..bb5295a 100644
--- a/node/expr/static_property_fetch.go
+++ b/node/expr/static_property_fetch.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // StaticPropertyFetch node
@@ -25,7 +26,7 @@ func (n *StaticPropertyFetch) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *StaticPropertyFetch) Walk(v node.Visitor) {
+func (n *StaticPropertyFetch) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/ternary.go b/node/expr/ternary.go
index 89cd2c4..8a4beac 100644
--- a/node/expr/ternary.go
+++ b/node/expr/ternary.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Ternary node
@@ -27,7 +28,7 @@ func (n *Ternary) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Ternary) Walk(v node.Visitor) {
+func (n *Ternary) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/unary_minus.go b/node/expr/unary_minus.go
index 2cb42dd..13596b7 100644
--- a/node/expr/unary_minus.go
+++ b/node/expr/unary_minus.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // UnaryMinus node
@@ -23,7 +24,7 @@ func (n *UnaryMinus) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *UnaryMinus) Walk(v node.Visitor) {
+func (n *UnaryMinus) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/unary_plus.go b/node/expr/unary_plus.go
index e0263ad..54fce81 100644
--- a/node/expr/unary_plus.go
+++ b/node/expr/unary_plus.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // UnaryPlus node
@@ -23,7 +24,7 @@ func (n *UnaryPlus) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *UnaryPlus) Walk(v node.Visitor) {
+func (n *UnaryPlus) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/variable.go b/node/expr/variable.go
index 4e4b58d..3fdcc4a 100644
--- a/node/expr/variable.go
+++ b/node/expr/variable.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Variable node
@@ -23,7 +24,7 @@ func (n *Variable) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Variable) Walk(v node.Visitor) {
+func (n *Variable) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/yield.go b/node/expr/yield.go
index e9ef29e..2e69148 100644
--- a/node/expr/yield.go
+++ b/node/expr/yield.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Yield node
@@ -25,7 +26,7 @@ func (n *Yield) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Yield) Walk(v node.Visitor) {
+func (n *Yield) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/expr/yield_from.go b/node/expr/yield_from.go
index 7036345..0674796 100644
--- a/node/expr/yield_from.go
+++ b/node/expr/yield_from.go
@@ -2,6 +2,7 @@ package expr
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // YieldFrom node
@@ -23,7 +24,7 @@ func (n *YieldFrom) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *YieldFrom) Walk(v node.Visitor) {
+func (n *YieldFrom) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/identifier.go b/node/identifier.go
index 8458b7a..8ccb716 100644
--- a/node/identifier.go
+++ b/node/identifier.go
@@ -1,5 +1,7 @@
 package node
 
+import "github.com/z7zmey/php-parser/walker"
+
 // Identifier node
 type Identifier struct {
 	Value string
@@ -21,7 +23,7 @@ func (n *Identifier) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Identifier) Walk(v Visitor) {
+func (n *Identifier) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/name/fully_qualified.go b/node/name/fully_qualified.go
index d973177..e215dd1 100644
--- a/node/name/fully_qualified.go
+++ b/node/name/fully_qualified.go
@@ -2,6 +2,7 @@ package name
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // FullyQualified node
@@ -23,7 +24,7 @@ func (n *FullyQualified) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *FullyQualified) Walk(v node.Visitor) {
+func (n *FullyQualified) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/name/name.go b/node/name/name.go
index d04f9d7..a1f68aa 100644
--- a/node/name/name.go
+++ b/node/name/name.go
@@ -2,6 +2,7 @@ package name
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Name node
@@ -23,7 +24,7 @@ func (n *Name) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Name) Walk(v node.Visitor) {
+func (n *Name) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/name/name_part.go b/node/name/name_part.go
index 4609289..a7629e2 100644
--- a/node/name/name_part.go
+++ b/node/name/name_part.go
@@ -1,8 +1,6 @@
 package name
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // NamePart node
 type NamePart struct {
@@ -25,7 +23,7 @@ func (n *NamePart) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *NamePart) Walk(v node.Visitor) {
+func (n *NamePart) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/name/name_test.go b/node/name/name_test.go
index 4d244d4..eb2958d 100644
--- a/node/name/name_test.go
+++ b/node/name/name_test.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/z7zmey/php-parser/node/expr"
 	"github.com/z7zmey/php-parser/node/name"
+	"github.com/z7zmey/php-parser/walker"
 
 	"github.com/kylelemons/godebug/pretty"
 	"github.com/z7zmey/php-parser/node"
@@ -124,12 +125,12 @@ type visitorMock struct {
 	visitedKeys   []string
 }
 
-func (v *visitorMock) EnterNode(n node.Node) bool { return v.visitChildren }
-func (v *visitorMock) GetChildrenVisitor(key string) node.Visitor {
+func (v *visitorMock) EnterNode(n walker.Walker) bool { return v.visitChildren }
+func (v *visitorMock) GetChildrenVisitor(key string) walker.Visitor {
 	v.visitedKeys = append(v.visitedKeys, key)
 	return &visitorMock{v.visitChildren, nil}
 }
-func (v *visitorMock) LeaveNode(n node.Node) {}
+func (v *visitorMock) LeaveNode(n walker.Walker) {}
 
 func TestNameVisitorDisableChildren(t *testing.T) {
 	for _, tt := range nameNodesTests {
diff --git a/node/name/relative.go b/node/name/relative.go
index 9fa1614..451febf 100644
--- a/node/name/relative.go
+++ b/node/name/relative.go
@@ -2,6 +2,7 @@ package name
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Relative node
@@ -23,7 +24,7 @@ func (n *Relative) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Relative) Walk(v node.Visitor) {
+func (n *Relative) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/node.go b/node/node.go
index 22a61d1..10c5ec9 100644
--- a/node/node.go
+++ b/node/node.go
@@ -1,14 +1,9 @@
 package node
 
+import "github.com/z7zmey/php-parser/walker"
+
 // Node interface
 type Node interface {
+	walker.Walker
 	Attributes() map[string]interface{} // Attributes returns node attributes as map
-	Walk(v Visitor)                     // Walk traverses nodes
-}
-
-// Visitor interface
-type Visitor interface {
-	EnterNode(node Node) bool              // EnterNode invoked for each node encountered by Walk.
-	GetChildrenVisitor(Key string) Visitor // GetChildrenVisitor returns visitor for children nodes
-	LeaveNode(node Node)                   // LeaveNode invoked after process node
 }
diff --git a/node/nullable.go b/node/nullable.go
index 70fe2e3..ee9f311 100644
--- a/node/nullable.go
+++ b/node/nullable.go
@@ -1,5 +1,7 @@
 package node
 
+import "github.com/z7zmey/php-parser/walker"
+
 // Nullable node
 type Nullable struct {
 	Expr Node
@@ -19,7 +21,7 @@ func (n *Nullable) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Nullable) Walk(v Visitor) {
+func (n *Nullable) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/parameter.go b/node/parameter.go
index ce6c82e..2e95d99 100644
--- a/node/parameter.go
+++ b/node/parameter.go
@@ -1,5 +1,7 @@
 package node
 
+import "github.com/z7zmey/php-parser/walker"
+
 // Parameter node
 type Parameter struct {
 	ByRef        bool
@@ -30,7 +32,7 @@ func (n *Parameter) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Parameter) Walk(v Visitor) {
+func (n *Parameter) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/scalar/dnumber.go b/node/scalar/dnumber.go
index 4e009f6..2674b48 100644
--- a/node/scalar/dnumber.go
+++ b/node/scalar/dnumber.go
@@ -1,8 +1,6 @@
 package scalar
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // Dnumber node
 type Dnumber struct {
@@ -25,7 +23,7 @@ func (n *Dnumber) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Dnumber) Walk(v node.Visitor) {
+func (n *Dnumber) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/scalar/encapsed.go b/node/scalar/encapsed.go
index 6243447..e21cc95 100644
--- a/node/scalar/encapsed.go
+++ b/node/scalar/encapsed.go
@@ -2,6 +2,7 @@ package scalar
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Encapsed node
@@ -23,7 +24,7 @@ func (n *Encapsed) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Encapsed) Walk(v node.Visitor) {
+func (n *Encapsed) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/scalar/encapsed_string_part.go b/node/scalar/encapsed_string_part.go
index 32b49cf..a37e089 100644
--- a/node/scalar/encapsed_string_part.go
+++ b/node/scalar/encapsed_string_part.go
@@ -1,8 +1,6 @@
 package scalar
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // EncapsedStringPart node
 type EncapsedStringPart struct {
@@ -25,7 +23,7 @@ func (n *EncapsedStringPart) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *EncapsedStringPart) Walk(v node.Visitor) {
+func (n *EncapsedStringPart) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/scalar/lnumber.go b/node/scalar/lnumber.go
index 3205572..7d9b8e0 100644
--- a/node/scalar/lnumber.go
+++ b/node/scalar/lnumber.go
@@ -1,8 +1,6 @@
 package scalar
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // Lnumber node
 type Lnumber struct {
@@ -25,7 +23,7 @@ func (n *Lnumber) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Lnumber) Walk(v node.Visitor) {
+func (n *Lnumber) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/scalar/magic_constant.go b/node/scalar/magic_constant.go
index 93e5530..6e10a89 100644
--- a/node/scalar/magic_constant.go
+++ b/node/scalar/magic_constant.go
@@ -1,8 +1,6 @@
 package scalar
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // MagicConstant node
 type MagicConstant struct {
@@ -25,7 +23,7 @@ func (n *MagicConstant) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *MagicConstant) Walk(v node.Visitor) {
+func (n *MagicConstant) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/scalar/string.go b/node/scalar/string.go
index cea5d10..10b6738 100644
--- a/node/scalar/string.go
+++ b/node/scalar/string.go
@@ -1,8 +1,6 @@
 package scalar
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // String node
 type String struct {
@@ -25,7 +23,7 @@ func (n *String) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *String) Walk(v node.Visitor) {
+func (n *String) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/scalar/visitor_test.go b/node/scalar/visitor_test.go
index fdbaf70..6a9d75a 100644
--- a/node/scalar/visitor_test.go
+++ b/node/scalar/visitor_test.go
@@ -7,6 +7,7 @@ import (
 	"github.com/kylelemons/godebug/pretty"
 	"github.com/z7zmey/php-parser/node"
 	"github.com/z7zmey/php-parser/node/scalar"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 var nameNodesTests = []struct {
@@ -51,12 +52,12 @@ type visitorMock struct {
 	visitedKeys   []string
 }
 
-func (v *visitorMock) EnterNode(n node.Node) bool { return v.visitChildren }
-func (v *visitorMock) GetChildrenVisitor(key string) node.Visitor {
+func (v *visitorMock) EnterNode(n walker.Walker) bool { return v.visitChildren }
+func (v *visitorMock) GetChildrenVisitor(key string) walker.Visitor {
 	v.visitedKeys = append(v.visitedKeys, key)
 	return &visitorMock{v.visitChildren, nil}
 }
-func (v *visitorMock) LeaveNode(n node.Node) {}
+func (v *visitorMock) LeaveNode(n walker.Walker) {}
 
 func TestNameVisitorDisableChildren(t *testing.T) {
 	for _, tt := range nameNodesTests {
diff --git a/node/stmt/alt_else.go b/node/stmt/alt_else.go
index 213d3dd..dc7045d 100644
--- a/node/stmt/alt_else.go
+++ b/node/stmt/alt_else.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // AltElse node
@@ -23,7 +24,7 @@ func (n *AltElse) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *AltElse) Walk(v node.Visitor) {
+func (n *AltElse) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/alt_else_if.go b/node/stmt/alt_else_if.go
index 870b82a..b0f0eee 100644
--- a/node/stmt/alt_else_if.go
+++ b/node/stmt/alt_else_if.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // AltElseIf node
@@ -25,7 +26,7 @@ func (n *AltElseIf) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *AltElseIf) Walk(v node.Visitor) {
+func (n *AltElseIf) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/alt_if.go b/node/stmt/alt_if.go
index 6b62230..3d6dd7c 100644
--- a/node/stmt/alt_if.go
+++ b/node/stmt/alt_if.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // AltIf node
@@ -45,7 +46,7 @@ func (n *AltIf) SetElse(Else node.Node) node.Node {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *AltIf) Walk(v node.Visitor) {
+func (n *AltIf) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/break.go b/node/stmt/break.go
index 8754d4f..aee2fa2 100644
--- a/node/stmt/break.go
+++ b/node/stmt/break.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Break node
@@ -23,7 +24,7 @@ func (n *Break) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Break) Walk(v node.Visitor) {
+func (n *Break) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/case.go b/node/stmt/case.go
index ec8acd0..43171e1 100644
--- a/node/stmt/case.go
+++ b/node/stmt/case.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Case node
@@ -25,7 +26,7 @@ func (n *Case) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Case) Walk(v node.Visitor) {
+func (n *Case) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/catch.go b/node/stmt/catch.go
index 7b7d08c..b289c7a 100644
--- a/node/stmt/catch.go
+++ b/node/stmt/catch.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Catch node
@@ -27,7 +28,7 @@ func (n *Catch) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Catch) Walk(v node.Visitor) {
+func (n *Catch) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/class.go b/node/stmt/class.go
index e6aefe8..af32994 100644
--- a/node/stmt/class.go
+++ b/node/stmt/class.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Class node
@@ -37,7 +38,7 @@ func (n *Class) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Class) Walk(v node.Visitor) {
+func (n *Class) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/class_const_list.go b/node/stmt/class_const_list.go
index cd80310..27262e1 100644
--- a/node/stmt/class_const_list.go
+++ b/node/stmt/class_const_list.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ClassConstList node
@@ -25,7 +26,7 @@ func (n *ClassConstList) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ClassConstList) Walk(v node.Visitor) {
+func (n *ClassConstList) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/class_method.go b/node/stmt/class_method.go
index b1306b8..669118e 100644
--- a/node/stmt/class_method.go
+++ b/node/stmt/class_method.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ClassMethod node
@@ -38,7 +39,7 @@ func (n *ClassMethod) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ClassMethod) Walk(v node.Visitor) {
+func (n *ClassMethod) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/const_list.go b/node/stmt/const_list.go
index 7d09790..7fda5dd 100644
--- a/node/stmt/const_list.go
+++ b/node/stmt/const_list.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ConstList node
@@ -23,7 +24,7 @@ func (n *ConstList) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ConstList) Walk(v node.Visitor) {
+func (n *ConstList) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/constant.go b/node/stmt/constant.go
index dabcdcd..8a1daba 100644
--- a/node/stmt/constant.go
+++ b/node/stmt/constant.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Constant node
@@ -29,7 +30,7 @@ func (n *Constant) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Constant) Walk(v node.Visitor) {
+func (n *Constant) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/continue.go b/node/stmt/continue.go
index 3011ff1..1c226af 100644
--- a/node/stmt/continue.go
+++ b/node/stmt/continue.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Continue node
@@ -23,7 +24,7 @@ func (n *Continue) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Continue) Walk(v node.Visitor) {
+func (n *Continue) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/declare.go b/node/stmt/declare.go
index 0a68aaf..1ba4539 100644
--- a/node/stmt/declare.go
+++ b/node/stmt/declare.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Declare node
@@ -25,7 +26,7 @@ func (n *Declare) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Declare) Walk(v node.Visitor) {
+func (n *Declare) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/default.go b/node/stmt/default.go
index 386b4de..d23c46d 100644
--- a/node/stmt/default.go
+++ b/node/stmt/default.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Default node
@@ -23,7 +24,7 @@ func (n *Default) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Default) Walk(v node.Visitor) {
+func (n *Default) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/do.go b/node/stmt/do.go
index 2f8e714..a5ca6f6 100644
--- a/node/stmt/do.go
+++ b/node/stmt/do.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Do node
@@ -25,7 +26,7 @@ func (n *Do) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Do) Walk(v node.Visitor) {
+func (n *Do) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/echo.go b/node/stmt/echo.go
index 1357a9d..cfea79a 100644
--- a/node/stmt/echo.go
+++ b/node/stmt/echo.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Echo node
@@ -23,7 +24,7 @@ func (n *Echo) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Echo) Walk(v node.Visitor) {
+func (n *Echo) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/else.go b/node/stmt/else.go
index bcaaf88..6b53200 100644
--- a/node/stmt/else.go
+++ b/node/stmt/else.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Else node
@@ -23,7 +24,7 @@ func (n *Else) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Else) Walk(v node.Visitor) {
+func (n *Else) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/else_if.go b/node/stmt/else_if.go
index 9a77e9e..f257828 100644
--- a/node/stmt/else_if.go
+++ b/node/stmt/else_if.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // ElseIf node
@@ -25,7 +26,7 @@ func (n *ElseIf) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *ElseIf) Walk(v node.Visitor) {
+func (n *ElseIf) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/expression.go b/node/stmt/expression.go
index 41bd4de..a3dc3c3 100644
--- a/node/stmt/expression.go
+++ b/node/stmt/expression.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Expression node
@@ -23,7 +24,7 @@ func (n *Expression) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Expression) Walk(v node.Visitor) {
+func (n *Expression) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/finally.go b/node/stmt/finally.go
index 692f096..1553f0d 100644
--- a/node/stmt/finally.go
+++ b/node/stmt/finally.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Finally node
@@ -23,7 +24,7 @@ func (n *Finally) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Finally) Walk(v node.Visitor) {
+func (n *Finally) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/for.go b/node/stmt/for.go
index aa07b40..a54de6e 100644
--- a/node/stmt/for.go
+++ b/node/stmt/for.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // For node
@@ -29,7 +30,7 @@ func (n *For) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *For) Walk(v node.Visitor) {
+func (n *For) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/foreach.go b/node/stmt/foreach.go
index 389a497..b38eda5 100644
--- a/node/stmt/foreach.go
+++ b/node/stmt/foreach.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Foreach node
@@ -33,7 +34,7 @@ func (n *Foreach) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Foreach) Walk(v node.Visitor) {
+func (n *Foreach) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/function.go b/node/stmt/function.go
index 396ae24..e90233b 100644
--- a/node/stmt/function.go
+++ b/node/stmt/function.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Function node
@@ -37,7 +38,7 @@ func (n *Function) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Function) Walk(v node.Visitor) {
+func (n *Function) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/global.go b/node/stmt/global.go
index 22d91c9..338f149 100644
--- a/node/stmt/global.go
+++ b/node/stmt/global.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Global node
@@ -23,7 +24,7 @@ func (n *Global) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Global) Walk(v node.Visitor) {
+func (n *Global) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/goto.go b/node/stmt/goto.go
index 64c0620..b3fd10c 100644
--- a/node/stmt/goto.go
+++ b/node/stmt/goto.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Goto node
@@ -23,7 +24,7 @@ func (n *Goto) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Goto) Walk(v node.Visitor) {
+func (n *Goto) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/group_use.go b/node/stmt/group_use.go
index 0ff0961..ca986b1 100644
--- a/node/stmt/group_use.go
+++ b/node/stmt/group_use.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // GroupUse node
@@ -32,7 +33,7 @@ func (n *GroupUse) SetUseType(UseType node.Node) node.Node {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *GroupUse) Walk(v node.Visitor) {
+func (n *GroupUse) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/halt_compiler.go b/node/stmt/halt_compiler.go
index 74d4ded..db90280 100644
--- a/node/stmt/halt_compiler.go
+++ b/node/stmt/halt_compiler.go
@@ -1,8 +1,6 @@
 package stmt
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // HaltCompiler node
 type HaltCompiler struct {
@@ -20,7 +18,7 @@ func (n *HaltCompiler) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *HaltCompiler) Walk(v node.Visitor) {
+func (n *HaltCompiler) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/if.go b/node/stmt/if.go
index ff3a165..ac7fb5c 100644
--- a/node/stmt/if.go
+++ b/node/stmt/if.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // If node
@@ -45,7 +46,7 @@ func (n *If) SetElse(_else node.Node) node.Node {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *If) Walk(v node.Visitor) {
+func (n *If) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/inline_html.go b/node/stmt/inline_html.go
index 65ff3e6..250ec4c 100644
--- a/node/stmt/inline_html.go
+++ b/node/stmt/inline_html.go
@@ -1,8 +1,6 @@
 package stmt
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // InlineHtml node
 type InlineHtml struct {
@@ -25,7 +23,7 @@ func (n *InlineHtml) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *InlineHtml) Walk(v node.Visitor) {
+func (n *InlineHtml) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/interface.go b/node/stmt/interface.go
index 181dd19..a7b9306 100644
--- a/node/stmt/interface.go
+++ b/node/stmt/interface.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Interface node
@@ -31,7 +32,7 @@ func (n *Interface) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Interface) Walk(v node.Visitor) {
+func (n *Interface) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/label.go b/node/stmt/label.go
index d1c5ad6..fa88c18 100644
--- a/node/stmt/label.go
+++ b/node/stmt/label.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Label node
@@ -23,7 +24,7 @@ func (n *Label) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Label) Walk(v node.Visitor) {
+func (n *Label) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/namespace.go b/node/stmt/namespace.go
index 016b0ff..b3b092d 100644
--- a/node/stmt/namespace.go
+++ b/node/stmt/namespace.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Namespace node
@@ -25,7 +26,7 @@ func (n *Namespace) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Namespace) Walk(v node.Visitor) {
+func (n *Namespace) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/nop.go b/node/stmt/nop.go
index 6ad4116..26047d8 100644
--- a/node/stmt/nop.go
+++ b/node/stmt/nop.go
@@ -1,8 +1,6 @@
 package stmt
 
-import (
-	"github.com/z7zmey/php-parser/node"
-)
+import "github.com/z7zmey/php-parser/walker"
 
 // Nop node
 type Nop struct {
@@ -20,7 +18,7 @@ func (n *Nop) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Nop) Walk(v node.Visitor) {
+func (n *Nop) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/property.go b/node/stmt/property.go
index f2e81f0..7746b99 100644
--- a/node/stmt/property.go
+++ b/node/stmt/property.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Property node
@@ -29,7 +30,7 @@ func (n *Property) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Property) Walk(v node.Visitor) {
+func (n *Property) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/property_list.go b/node/stmt/property_list.go
index 7711c95..bee9e62 100644
--- a/node/stmt/property_list.go
+++ b/node/stmt/property_list.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // PropertyList node
@@ -25,7 +26,7 @@ func (n *PropertyList) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *PropertyList) Walk(v node.Visitor) {
+func (n *PropertyList) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/return.go b/node/stmt/return.go
index 4c0df9e..22047a9 100644
--- a/node/stmt/return.go
+++ b/node/stmt/return.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Return node
@@ -23,7 +24,7 @@ func (n *Return) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Return) Walk(v node.Visitor) {
+func (n *Return) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/static.go b/node/stmt/static.go
index 5a55a6e..8ec10b9 100644
--- a/node/stmt/static.go
+++ b/node/stmt/static.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Static node
@@ -23,7 +24,7 @@ func (n *Static) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Static) Walk(v node.Visitor) {
+func (n *Static) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/static_var.go b/node/stmt/static_var.go
index aaf92ae..157d2f6 100644
--- a/node/stmt/static_var.go
+++ b/node/stmt/static_var.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // StaticVar node
@@ -25,7 +26,7 @@ func (n *StaticVar) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *StaticVar) Walk(v node.Visitor) {
+func (n *StaticVar) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/stmt_list.go b/node/stmt/stmt_list.go
index 07be0e5..fa2e391 100644
--- a/node/stmt/stmt_list.go
+++ b/node/stmt/stmt_list.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // StmtList node
@@ -23,7 +24,7 @@ func (n *StmtList) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *StmtList) Walk(v node.Visitor) {
+func (n *StmtList) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/switch.go b/node/stmt/switch.go
index 75b7874..2363fc6 100644
--- a/node/stmt/switch.go
+++ b/node/stmt/switch.go
@@ -3,6 +3,7 @@ package stmt
 import (
 	"github.com/z7zmey/php-parser/node"
 	"github.com/z7zmey/php-parser/token"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Switch node
@@ -28,7 +29,7 @@ func (n *Switch) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Switch) Walk(v node.Visitor) {
+func (n *Switch) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/throw.go b/node/stmt/throw.go
index d1750b1..5d510f2 100644
--- a/node/stmt/throw.go
+++ b/node/stmt/throw.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Throw node
@@ -23,7 +24,7 @@ func (n *Throw) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Throw) Walk(v node.Visitor) {
+func (n *Throw) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/trait.go b/node/stmt/trait.go
index 367538e..24b3fed 100644
--- a/node/stmt/trait.go
+++ b/node/stmt/trait.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Trait node
@@ -29,7 +30,7 @@ func (n *Trait) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Trait) Walk(v node.Visitor) {
+func (n *Trait) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/trait_method_ref.go b/node/stmt/trait_method_ref.go
index 51e2c5c..26ec510 100644
--- a/node/stmt/trait_method_ref.go
+++ b/node/stmt/trait_method_ref.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // TraitMethodRef node
@@ -25,7 +26,7 @@ func (n *TraitMethodRef) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *TraitMethodRef) Walk(v node.Visitor) {
+func (n *TraitMethodRef) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/trait_use.go b/node/stmt/trait_use.go
index 886f2c4..a92fd5b 100644
--- a/node/stmt/trait_use.go
+++ b/node/stmt/trait_use.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // TraitUse node
@@ -25,7 +26,7 @@ func (n *TraitUse) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *TraitUse) Walk(v node.Visitor) {
+func (n *TraitUse) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/trait_use_alias.go b/node/stmt/trait_use_alias.go
index f43b58a..537718f 100644
--- a/node/stmt/trait_use_alias.go
+++ b/node/stmt/trait_use_alias.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // TraitUseAlias node
@@ -27,7 +28,7 @@ func (n *TraitUseAlias) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *TraitUseAlias) Walk(v node.Visitor) {
+func (n *TraitUseAlias) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/trait_use_precedence.go b/node/stmt/trait_use_precedence.go
index 5f1a643..43f3949 100644
--- a/node/stmt/trait_use_precedence.go
+++ b/node/stmt/trait_use_precedence.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // TraitUsePrecedence node
@@ -25,7 +26,7 @@ func (n *TraitUsePrecedence) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *TraitUsePrecedence) Walk(v node.Visitor) {
+func (n *TraitUsePrecedence) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/try.go b/node/stmt/try.go
index 1c65059..80d26b2 100644
--- a/node/stmt/try.go
+++ b/node/stmt/try.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Try node
@@ -27,7 +28,7 @@ func (n *Try) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Try) Walk(v node.Visitor) {
+func (n *Try) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/unset.go b/node/stmt/unset.go
index 887e9c1..e301d69 100644
--- a/node/stmt/unset.go
+++ b/node/stmt/unset.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Unset node
@@ -23,7 +24,7 @@ func (n *Unset) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Unset) Walk(v node.Visitor) {
+func (n *Unset) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/use.go b/node/stmt/use.go
index b53e249..a74d617 100644
--- a/node/stmt/use.go
+++ b/node/stmt/use.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // Use node
@@ -32,7 +33,7 @@ func (n *Use) SetUseType(UseType node.Node) node.Node {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *Use) Walk(v node.Visitor) {
+func (n *Use) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/use_list.go b/node/stmt/use_list.go
index 332cac1..f7d59fd 100644
--- a/node/stmt/use_list.go
+++ b/node/stmt/use_list.go
@@ -2,6 +2,7 @@ package stmt
 
 import (
 	"github.com/z7zmey/php-parser/node"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // UseList node
@@ -25,7 +26,7 @@ func (n *UseList) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *UseList) Walk(v node.Visitor) {
+func (n *UseList) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/stmt/while.go b/node/stmt/while.go
index 4627f16..9fc6a48 100644
--- a/node/stmt/while.go
+++ b/node/stmt/while.go
@@ -3,6 +3,7 @@ package stmt
 import (
 	"github.com/z7zmey/php-parser/node"
 	"github.com/z7zmey/php-parser/token"
+	"github.com/z7zmey/php-parser/walker"
 )
 
 // While node
@@ -28,7 +29,7 @@ func (n *While) Attributes() map[string]interface{} {
 
 // Walk traverses nodes
 // Walk is invoked recursively until v.EnterNode returns true
-func (n *While) Walk(v node.Visitor) {
+func (n *While) Walk(v walker.Visitor) {
 	if v.EnterNode(n) == false {
 		return
 	}
diff --git a/node/visitor_test.go b/node/visitor_test.go
index a2079b2..b7f38a7 100644
--- a/node/visitor_test.go
+++ b/node/visitor_test.go
@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/z7zmey/php-parser/node/scalar"
+	"github.com/z7zmey/php-parser/walker"
 
 	"github.com/z7zmey/php-parser/node/expr"
 
@@ -50,12 +51,12 @@ type visitorMock struct {
 	visitedKeys   []string
 }
 
-func (v *visitorMock) EnterNode(n node.Node) bool { return v.visitChildren }
-func (v *visitorMock) GetChildrenVisitor(key string) node.Visitor {
+func (v *visitorMock) EnterNode(n walker.Walker) bool { return v.visitChildren }
+func (v *visitorMock) GetChildrenVisitor(key string) walker.Visitor {
 	v.visitedKeys = append(v.visitedKeys, key)
 	return &visitorMock{v.visitChildren, nil}
 }
-func (v *visitorMock) LeaveNode(n node.Node) {}
+func (v *visitorMock) LeaveNode(n walker.Walker) {}
 
 func TestNameVisitorDisableChildren(t *testing.T) {
 	for _, tt := range nodesToTest {
diff --git a/parser/parser.go b/parser/parser.go
index dd896fe..d48e701 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -5,6 +5,10 @@ import __yyfmt__ "fmt"
 
 //line parser/parser.y:2
 import (
+	"io"
+	"strconv"
+	"strings"
+
 	"github.com/z7zmey/php-parser/comment"
 	"github.com/z7zmey/php-parser/node"
 	"github.com/z7zmey/php-parser/node/expr"
@@ -16,9 +20,6 @@ import (
 	"github.com/z7zmey/php-parser/node/stmt"
 	"github.com/z7zmey/php-parser/position"
 	"github.com/z7zmey/php-parser/token"
-	"io"
-	"strconv"
-	"strings"
 )
 
 var rootnode node.Node
diff --git a/parser/scanner.go b/parser/scanner.go
index 8784979..7d2d332 100644
--- a/parser/scanner.go
+++ b/parser/scanner.go
@@ -11,6 +11,7 @@ package parser
 import (
 	"bytes"
 	"fmt"
+
 	"github.com/cznic/golex/lex"
 	"github.com/z7zmey/php-parser/comment"
 )
diff --git a/walker/walker.go b/walker/walker.go
new file mode 100644
index 0000000..034a6cd
--- /dev/null
+++ b/walker/walker.go
@@ -0,0 +1,13 @@
+package walker
+
+// Walker interface
+type Walker interface {
+	Walk(v Visitor)
+}
+
+// Visitor interface
+type Visitor interface {
+	EnterNode(w Walker) bool               // EnterNode invoked for each node encountered by Walk.
+	GetChildrenVisitor(Key string) Visitor // GetChildrenVisitor returns visitor for children nodes
+	LeaveNode(w Walker)                    // LeaveNode invoked after process node
+}