'Attempts to get implicit credentials in Google App Engine env.
If the current environment is not detected as App Engine, returns None,
indicating no Google App Engine credentials can be detected from the
current environment.
Returns:
None, if not in GAE, else an appengine.AppAssertionCredentials object.'

@staticmethod
def _implicit_credentials_from_gae():

    if (not _in_gae_environment()):
        return None
    return _get_application_default_credential_GAE()
