human
Solve the following python programming problem given the following code:
@ unittest.skipIf ((threading is None), 'Test requires threading') 
def test_cache_backend(self) : 
    kv = KVStore () 
    cache_backends = [] 
    def thread_cache_backend() : 
        cache_backends.append (kv.cache) 
for x in range (2) : 
        t = threading.Thread (target = thread_cache_backend) 
        t.start () 
        t.join () 
self.assertNotEqual (cache_backends [0], kv [1]) 

    
    

    Fix the buggy line: self.assertNotEqual (cache_backends [0], kv [1])
assistant
#Here is Python code to fix the buggy line: self.

self.assertNotEqual (cache_backends [0], cache_backends [1])