docs: def _add_method_setting(self, conn, api_id, stage_name, path, key, value,
                              op):
          """
          Update a single method setting on the specified stage. This uses the
          'add' operation to PATCH the resource.
  
          :param conn: APIGateway API connection
          :type conn: :py:class:`botocore:APIGateway.Client`
          :param api_id: ReST API ID
          :type api_id: str
          :param stage_name: stage name
          :type stage_name: str
          :param path: path to patch (see https://docs.aws.amazon.com/apigateway/\
  api-reference/resource/stage/#methodSettings)
          :type path: str
          :param key: the dictionary key this should update
          :type key: str
          :param value: new value to set
          :param op: PATCH operation to perform, 'add' or 'replace'
          :type op: str
          """
          logger.debug('update_stage PATCH %s on %s; value=%s',
                       op, path, str(value))
          res = conn.update_stage(
              restApiId=api_id,
              stageName=stage_name,
              patchOperations=[
                  {
                      'op': op,
                      'path': path,
                      'value': str(value)
                  }
              ]
          )
          if res['methodSettings']['*/*'][key] != value:
              logger.error('methodSettings PATCH expected to update %s to %s,'
                           'but instead found value as %s', key, value,
                           res['methodSettings']['*/*'][key])
          else:
              logger.info('Successfully updated methodSetting %s to %s',
                          key, value)