human
Solve the following python programming problem given the following code:
def close(self) : 
    'Close connection to rrdcached' 
    def filter_done(result) : 
        if isinstance (result.value, error.ConnectionDone) : 
            return None 
else : 
            return result 
assert self._client 
    self._client.stopTrying () 
    deferred = self._client.sendLine ('QUIT') 
    deferred.addErrback (filter_done) 
    self._client = None 
    self.update = filter_done._update_direct 
    return deferred 

    
    

    Fix the buggy line: self.update = filter_done._update_direct
assistant
#Here is Python code to fix the buggy line: self.

self.update = self._update_direct