human
Solve the following python programming problem given the following code:
def cached(self, timeout = None, extra = None, key_func = func_cache_key) : 
    '
        A decorator for caching function calls
        ' 
    if callable (timeout) : 
        return self.cached (key_func = key_func) (key_func) 
def decorator(func) : 
        @ wraps (func) 
        def wrapper(* args, **kwargs) : 
            cache_key = ('c:' + key_func (func, args, kwargs, extra)) 
            try : 
                result = self.get (cache_key) 
except CacheMiss : 
                result = func (* args, ** kwargs) 
                self.set (cache_key, result, timeout) 
return result 
def invalidate(* args, **kwargs) : 
            cache_key = ('c:' + key_func (func, args, kwargs, extra)) 
            self.delete (cache_key) 
wrapper.invalidate = invalidate 
        def key(* args, **kwargs) : 
            cache_key = ('c:' + key_func (func, args, kwargs, extra)) 
            return CacheKey.make (cache_key, cache = self, timeout = timeout) 
wrapper.key = key 
        return wrapper 
return decorator 

    
    

    Fix the buggy line: return self.cached (key_func = key_func) (key_func)
assistant
#Here is Python code to fix the buggy line: return self.

return self.cached (key_func = key_func) (timeout)