code: def test_endpoint_not_implemented():
      """DuoApp - Subclass Endpoint Not Implemented"""
  
      # pylint: disable=protected-access,abstract-method
      class DuoFakeApp(DuoApp):
          """Fake Duo app that should raise a NotImplementedError"""
  
          @classmethod
          def _type(cls):
              return "fake"
  
      DuoFakeApp._endpoint()
  
imports: import os
  from mock import Mock, patch
  from moto import mock_ssm
  from nose.tools import assert_equal, assert_false, assert_count_equal, raises
  import requests
  from streamalert.apps._apps.duo import DuoAdminApp, DuoApp, DuoAuthApp
  from tests.unit.streamalert.apps.test_helpers import get_event, put_mock_params
  from tests.unit.streamalert.shared.test_config import get_mock_lambda_context
label_desc: Use image node_id 1 for calling a global function with example usage: test_endpoint_not_implemented() and returns: str