How to implement MAC_X919 algorithm in Python

mac_x919.py

#!/usr/bin/env python2

import Crypto.Cipher.DES as des
import Crypto.Cipher.DES3 as des3

def mac_x919(key,data):
  while len(data) % 8 != 0:
    data += '\x00'
  des_key1 = des.new(key[0:8],des.MODE_CBC)
  des_key2 = des.new(key[0:8],des.MODE_ECB)
  buf = des_key1.encrypt(data)
  buf = buf[len(buf)-8:]
  buf = des_key2.decrypt(buf)
  des3_key = des3.new(key,des3.MODE_ECB)
  buf = des3_key.encrypt(buf)
  return buf[0:4]

mac = mac_x919('0123456789abcdef','test data to be encrypted')