modified to allow the ns and nsDefs accessors to return None instead of

* python/generator.py: modified to allow the ns and nsDefs
  accessors to return None instead of error when no namespace
  is present (bug #)
diff --git a/python/generator.py b/python/generator.py
index 6032065..6f5ee09 100755
--- a/python/generator.py
+++ b/python/generator.py
@@ -735,6 +735,8 @@
     "xmlHasProp": 1,
     "xmlHasNsProp": 1,
     "xmlDocSetRootElement": 1,
+    "xmlNodeGetNs": 1,
+    "xmlNodeGetNsDefs": 1,
 }
 
 reference_keepers = {