Ran 2to3 over scripts directory.
diff --git a/Tools/scripts/nm2def.py b/Tools/scripts/nm2def.py
index 5f2bc8f..9dfb991 100755
--- a/Tools/scripts/nm2def.py
+++ b/Tools/scripts/nm2def.py
@@ -84,7 +84,7 @@
 
 def filter_Python(symbols,specials=SPECIALS):
 
-    for name in symbols.keys():
+    for name in list(symbols.keys()):
         if name[:2] == 'Py' or name[:3] == '_Py':
             pass
         elif name not in specials: