def decode(data):
    """
    Decode the multibase decoded data
    :param data: multibase encoded data
    :type data: str or bytes
    :return: decoded data
    :rtype: str
    :raises ValueError: if the data is not multibase encoded
    """
    data = ensure_bytes(data, 'utf8')
    codec = get_codec(data)
    return codec.converter.decode(data[CODE_LENGTH:])