code: def get_api_keys(self, api_id, stage_name):
          
          response = self.apigateway_client.get_api_keys(limit=500)
          stage_key = '{}/{}'.format(api_id, stage_name)
          for api_key in response.get('items'):
              if stage_key in api_key.get('stageKeys'):
                  yield api_key.get('id')
docs: Generator that allows to iterate per API keys associated to an api_id and a stage_name.