def test_generate(self):
     tiny_url = TinyURL()
     self.assertEqual(
         tiny_url.generate('aaa'), '0')
 def test_lookup(self):
     tiny_url = TinyURL()
     self.assertEqual(
         tiny_url.lookup(tiny_url.generate('bbb')), 'bbb')
     self.assertEqual(
         tiny_url.lookup('ccc'), None)