Update the contents of this periodically sent message.

        Note the Message must have the same :attr:`~can.Message.arbitration_id`
        like the first message.

def modify_data(self, message):
        """Update the contents of this periodically sent message.

        Note the Message must have the same :attr:`~can.Message.arbitration_id`
        like the first message.
        """
        assert message.arbitration_id == self.can_id, "You cannot modify the can identifier"
        self.message = message
        header = build_bcm_update_header(self.can_id_with_flags, self.flags)
        frame = build_can_frame(message)
        send_bcm(self.bcm_socket, header + frame)