http = httplib2.Http()
service = build('helloworld', 'v1', http=http, discoveryServiceUrl=
    'http://localhost:8080/_ah/api/discovery/v1/apis/helloworld/v1/rest')
print(service.greetings().listGreeting().execute()['items'])
"""
prints
[{u'message': u'hello world!'}, {u'message': u'goodbye world!'}]
"""
Consuming GAE Endpoints with a Python client