code: def unpack_mac(sixbytes):
  	
  	if not isinstance(sixbytes, bytes):
  		raise ValueError("given buffer is not a string")
  	if len(sixbytes) != 6:
  		raise ValueError("given buffer is not exactly six bytes long")
  	return ":".join(["%2.2x".__mod__(x) for x in bytes_to_int_seq(sixbytes)])
docs: Converts a mac address given in a six byte string in network
  	byte order to a string in colon delimited notation.
  
  	>>> unpack_mac(b"012345")
  	'30:31:32:33:34:35'
  	>>> unpack_mac(b"bad")
  	Traceback (most recent call last):
  	...
  	ValueError: given buffer is not exactly six bytes long
  
  	@type sixbytes: bytes
  	@rtype: str
  	@raises ValueError: for bad input