def get_request(request_id, request_type):
    """Get the data associated with the request id, or None.

        :param request_id: The unique id for the request.
        :type request_id: int
        :param request_type: Optional request type that the requested id must
            match, otherwise no match is returned.
        :type request_type: `RequestType`
        :return: A 2-tuple of the key and data originally held, or None if the
            `request_id` is not in the database.
        """
