'signature(value, salt=...) should work'

def test_signature_with_salt(self):

    signer = signing.Signer('predictable-secret', salt='extra-salt')
    self.assertEqual(signer.signature('hello'), signing.base64_hmac(('extra-salt' + 'signer'), 'hello', 'predictable-secret'))
    self.assertNotEqual(signing.Signer('predictable-secret', salt='one').signature('hello'), signing.Signer('predictable-secret', salt='two').signature('hello'))
