docs: def get_suitable_app(cls, given_app):
          u"""
          Return a clone of given_app with ChordableDjangoBackend, if needed.
          """
          if not isinstance(getattr(given_app, 'backend', None), ChordableDjangoBackend):
              return_app = deepcopy(given_app)
              return_app.backend = ChordableDjangoBackend(return_app)
              return return_app
          else:
              return given_app