def METHOD_NAME(cls, raw_chunk):
    if not raw_chunk.startswith('_ibdmp:'):
        LOG_WARN("invalid chunk payload (no '_ibdmp:'?): %s"
                 % raw_chunk)
        raise IbdmpDecodeError(raw_chunk)
    areas = raw_chunk.split('|')
    parts = areas[1].split(':')
    return cls(
        ordinal=int(parts[0]),
        payload=str(parts[1]),
    )