diff --git a/treelib/tree.py b/treelib/tree.py
index 6ee18c9..21a284c 100644
--- a/treelib/tree.py
+++ b/treelib/tree.py
@@ -186,11 +186,6 @@ def get_label(node):
                 def get_label(node):
                     return "%s[%s]" % (node.tag, node.identifier)
 
-        # legacy ordering
-        if key is None:
-            def key(node):
-                return node
-
         # iter with func
         for pre, node in self.__get(nid, level, filter, key, reverse,
                                     line_type):