diff --git a/alib2std/src/extensions/forward_tree.hpp b/alib2std/src/extensions/forward_tree.hpp
index 38ccdc105b582e16438a374a0d5c33ec074b466e..04712970b6f31c3287dd29a32c68be020d45b7b2 100644
--- a/alib2std/src/extensions/forward_tree.hpp
+++ b/alib2std/src/extensions/forward_tree.hpp
@@ -10,14 +10,6 @@
 
 namespace std {
 
-/*template < class T >
-struct AnyArity {
-	bool operator ()( const T &, unsigned ) const {
-		return true;
-	}
-
-};*/
-
 template < class T, class ArityChecker = AnyArity < T > >
 class forward_tree {
 
diff --git a/alib2std/src/extensions/tree.hpp b/alib2std/src/extensions/tree.hpp
index 653b3a77139b9031f73c180a1167b59d09c9cfc0..4f628847255de22e7cafc93a8a5f135bd589ae26 100644
--- a/alib2std/src/extensions/tree.hpp
+++ b/alib2std/src/extensions/tree.hpp
@@ -10,14 +10,6 @@
 
 namespace std {
 
-template < class T >
-struct AnyArity {
-	bool operator ()( const T &, unsigned ) const {
-		return true;
-	}
-
-};
-
 template < class T, class ArityChecker = AnyArity < T > >
 class tree {
 
diff --git a/alib2std/src/extensions/tree_base.hpp b/alib2std/src/extensions/tree_base.hpp
index 031aadfc5f78deb07720806024bbb0e8151602d4..5a8cfc7397276d1d54c6e5a67ab60832bbce24d1 100644
--- a/alib2std/src/extensions/tree_base.hpp
+++ b/alib2std/src/extensions/tree_base.hpp
@@ -10,6 +10,14 @@
 
 namespace std {
 
+template < class T >
+struct AnyArity {
+	bool operator ()( const T &, unsigned ) const {
+		return true;
+	}
+
+};
+
 template < class Data >
 class BaseNode {
 	Data * parent;