def METHOD_NAME(s: BinaryIO) -> int:
    """
    Unpack a PER length indicator
    :param s: stream
    """
    byte = Uint8.unpack(s.read(1))
    if byte & 0x80:
        byte &= ~0x80
        return (byte << 8) + Uint8.unpack(s.read(1))
    else:
        return byte