message: Create mac package.
diff: @@ -6,9 +6,12 @@ from __future__ import print_function
  from google3.third_party.tink.python import aead
  from google3.third_party.tink.python import key_manager
  +from google3.third_party.tink.python import mac
  from google3.third_party.tink.python import tink_config
  +
  Aead = aead.Aead
  +Mac = mac.Mac
  KeyManager = key_manager.KeyManager
  PrivateKeyManager = key_manager.PrivateKeyManager
  