@classmethod
def create(cls, request, **fields):
    """
        Create a response to the given request.

        Fields and their values can be passed in to pre-populate the response
        as keyword arguments, or can be set individually on the resulting
        response.
        """
    if request.is_created:
        raise ValueError("can't respond to requests we created")
    request._source.relation.to_publish['response_' + request.request_id
        ] = fields
    response = cls(request)
    request.response = response
    return response
