code: def get_required_headers(service, endpoint):
          
          headers = {}
          headers.update(service.required_headers)
          headers.update(endpoint.required_headers)
          return headers
docs: :param Service service:
              The service being called
          :param Endpoint endpoint:
              The endpoint being called
          :return:
              Headers required by the ``service`` and the ``endpoint`` being called
          :rtype:
              dict