'Passing in None into timeout results in a value that is cached forever'

def test_forever_timeout(self):

    self.cache.set(u'key1', u'eggs', None)
    self.assertEqual(self.cache.get(u'key1'), u'eggs')
    self.cache.add(u'key2', u'ham', None)
    self.assertEqual(self.cache.get(u'key2'), u'ham')
    self.cache.set_many({u'key3': u'sausage', u'key4': u'lobster    bisque'}, None)
    self.assertEqual(self.cache.get(u'key3'), u'sausage')
    self.assertEqual(self.cache.get(u'key4'), u'lobster    bisque')
