How To fix the error returned by dev_appserver.py

Please Help! It's my first project using app engine. I've created the app with the required files. But when I try starting the server in the cloud sdk cmd (and other cmd programs) it returns an error relating to Method Resolution Order (MRO).

I tried running the dev_appserver.py from both the folder containing the gcloud skd (while supplying the application forlder) and the application folder (c:\path-to-app>dev_appserver.py) Please see the error below:

D:\AMINU BISHIR\AMINU BISHIR\PROGRAMMING\Full Stack Web\Programs\my_app_engine>dev_appserver.py .
Traceback (most recent call last):
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\bin\dev_appserver.py", line 14, in <module>
    from bootstrapping import bootstrapping
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\bin\bootstrapping\bootstrapping.py", line 46, in <module>
    from googlecloudsdk.core.updater import update_manager
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\lib\googlecloudsdk\core\updater\update_manager.py", line 35, in <module>
    from googlecloudsdk.core import yaml
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\lib\googlecloudsdk\core\yaml.py", line 29, in <module>
    from googlecloudsdk.core import yaml_location_value
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\lib\googlecloudsdk\core\yaml_location_value.py", line 39, in <module>
    from ruamel import yaml
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\lib\third_party\ruamel\yaml\__init__.py", line 85, in <module>
    from ruamel.yaml.main import *  # NOQA
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\lib\third_party\ruamel\yaml\main.py", line 19, in <module>
    from ruamel.yaml.loader import BaseLoader, SafeLoader, Loader, RoundTripLoader  # NOQA
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\lib\third_party\ruamel\yaml\loader.py", line 10, in <module>
    from ruamel.yaml.constructor import (
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\lib\third_party\ruamel\yaml\constructor.py", line 21, in <module>
    from ruamel.yaml.comments import *                               # NOQA
  File "C:\Users\Sadarwa\AppData\Local\Google\Cloud SDK\google-cloud-sdk\lib\third_party\ruamel\yaml\comments.py", line 642, in <module>
    class CommentedMap(MutableMapping, ordereddict, CommentedBase):
  File "C:\Python27\lib\abc.py", line 86, in __new__
    cls = super(ABCMeta, mcls).__new__(mcls, name, bases, namespace)
TypeError: Error when calling the metaclass bases
    Cannot create a consistent method resolution
order (MRO) for bases ordereddict, MutableMapping, CommentedBase