docs: def _user_settings(self):
          """
          Resolve settings dict from django settings module.
          Validate that all the required keys are present and also that none of
          the removed keys do.
          Result is cached.
          """
          user_settings = getattr(settings, self._name, {})
          if not user_settings and self._required:
              raise ImproperlyConfigured("Settings file is missing dict options with name {}".format(self._name))
          keys = frozenset(user_settings.keys())
  
          required = self._required - keys
          if required:
              raise ImproperlyConfigured("Following options for {} are missing from settings file: {}".format(self._name, ', '.join(sorted(required))))
  
          removed = keys & self._removed
          if removed:
              raise ImproperlyConfigured("Following options for {} have been removed: {}".format(self._name, ', '.join(sorted(removed))))
  
          return user_settings