human
Solve the following python programming problem given the following code:
def DeferredSerializer(original, context) : 
    '
    Serialize the result of the given Deferred without affecting its result.

    @type original: L{defer.Deferred}
    @param original: The Deferred being serialized.

    @rtype: L{defer.Deferred}
    @return: A Deferred which will be called back with the result of
        serializing the result of C{original} or which will errback if
        either C{original} errbacks or there is an error serializing the
        result of C{original}.
    ' 
    d = defer.Deferred () 
    def cb(result) : 
        d2 = defer.maybeDeferred (flat.serialize, result, context) 
        d2.chainDeferred (d) 
        return result 
def eb(error) : 
        d.errback (error) 
        return error 
original.addCallbacks (cb, cb) 
    return d 

    
    

    Fix the buggy line: original.addCallbacks (cb, cb)
assistant
#Here is Python code to fix the buggy line: original.

original.addCallbacks (cb, def eb()