Create a resource of the resource.

        This should only be called from sub-classes

        Args:

          session(Session): The session to create the resource in.

          attributes(dict): Any attributes that are valid for the
              given resource type.

          relationships(dict): Any relationships that are valid for the
              given resource type.

        Returns:

          Resource: An instance of a resource.

def create(cls, session, attributes=None, relationships=None):
        """Create a resource of the resource.

        This should only be called from sub-classes

        Args:

          session(Session): The session to create the resource in.

          attributes(dict): Any attributes that are valid for the
              given resource type.

          relationships(dict): Any relationships that are valid for the
              given resource type.

        Returns:

          Resource: An instance of a resource.

        """
        resource_type = cls._resource_type()
        resource_path = cls._resource_path()
        url = session._build_url(resource_path)
        json = build_request_body(resource_type, None,
                                  attributes=attributes,
                                  relationships=relationships)
        process = cls._mk_one(session)
        return session.post(url, CB.json(201, process), json=json)