comment out unnecessary walker methods

Author: Robbybp

Diff for: pyomo/util/subsystems.py

@@ -56,13 +56,13 @@ def exitNode(self, node, data):
     def finalizeResult(self, result):
         return self._functions
 
-    def enterNode(self, node):
-        pass
+    #def enterNode(self, node):
+    #    pass
 
-    def acceptChildResult(self, node, data, child_result, child_idx):
-        if child_result.__class__ in native_types:
-            return False, None
-        return child_result.is_expression_type(), None
+    #def acceptChildResult(self, node, data, child_result, child_idx):
+    #    if child_result.__class__ in native_types:
+    #        return False, None
+    #    return child_result.is_expression_type(), None
 
 
 def identify_external_functions(expr):