Define SimpleNamespace on python 2

notebook/tests/test_serverextensions.py

@@ -17,8 +17,12 @@ from notebook import nbextensions
 from notebook.notebookapp import NotebookApp
 from notebook.nbextensions import _get_config_dir
 
+if sys.version_info > (3,):
+    from types import SimpleNamespace
+else:
+    class SimpleNamespace(object):
+        pass
 
-from types import SimpleNamespace
 from collections import OrderedDict