code: def configure_createfor(self, ns, definition):
          
          @self.add_route(ns.relation_path, Operation.CreateFor, ns)
          @request(definition.request_schema)
          @response(definition.response_schema)
          @wraps(definition.func)
          def create(**path_data):
              request_data = load_request_data(definition.request_schema)
              response_data = require_response_data(definition.func(**merge_data(path_data, request_data)))
              headers = encode_id_header(response_data)
              definition.header_func(headers, response_data)
              response_format = self.negotiate_response_content(definition.response_formats)
              return dump_response_data(
                  definition.response_schema,
                  response_data,
                  Operation.CreateFor.value.default_code,
                  headers=headers,
                  response_format=response_format,
              )
  
          create.__doc__ = "Create a new {} relative to a {}".format(pluralize(ns.object_name), ns.subject_name)
docs: Register a create-for relation endpoint.
  
          The definition's func should be a create function, which must:
          - accept kwargs for the new instance creation parameters
          - return the created instance
  
          :param ns: the namespace
          :param definition: the endpoint definition