def METHOD_NAME(self, data):
    """
    Add more ``data`` to the message.
    """
    if isinstance(data, bytes):
        self.data += data
    elif isinstance(data, bytearray):
        self.data += bytes(data)
    elif isinstance(data, unicode):
        self.data += data.encode(self.encoding)
    else:
        raise TypeError("%s is not a supported data type" % type(data))