def test_empty(self):
     self.assertIs(validate(''), False)
 def test_zero(self):
     self.assertIs(validate('0'), True)
 def test_not_valid(self):
     self.assertIs(validate('4123412341234123'), False)
 def test_amex(self):
     self.assertIs(validate('343539069275686'), True)
 def test_mastercard(self):
     self.assertIs(validate('5490745468338088'), True)
 def test_visa_no_nines(self):
     self.assertIs(validate('4743803307345687'), True)
 def test_visa(self):
     self.assertIs(validate('4743903107345687'), True)