code: def parse(cls, detail_string):
          
          split = detail_string.split(':')
          if len(split) != 4:
              raise Exception('invalid credentials')  # TODO: other exception
  
          ltpk = binascii.unhexlify(split[0])
          ltsk = binascii.unhexlify(split[1])
          atv_id = binascii.unhexlify(split[2])
          client_id = binascii.unhexlify(split[3])
          return Credentials(ltpk, ltsk, atv_id, client_id)
docs: Parse a string represention of Credentials.