def _generate_MAC(segments=6, segment_length=2, delimiter=":", charset="0123456789abcdef"):
        """generate a non-guaranteed-unique mac address"""
        addr = []
        for _ in range(segments):
            sub = ''.join(random.choice(charset) for _ in range(segment_length))
            addr.append(sub)
        return delimiter.join(addr)
generate a non-guaranteed-unique mac address