human
Solve the following python programming problem given the following code:
def close(self, **kw) : 
    '
        This asks Tor to close the underlying circuit object. See
        :meth:`txtorcon.torstate.TorState.close_circuit`
        for details.

        You may pass keyword arguments to take care of any Flags Tor
        accepts for the CLOSECIRCUIT command. Currently, this is only
        "IfUnused". So for example: circ.close(IfUnused=True)

        :return: Deferred which callbacks with this Circuit instance
        ONLY after Tor has confirmed it is gone (not simply that the
        CLOSECIRCUIT command has been queued). This could be a while
        if you included IfUnused.
        ' 
    self._closing_deferred = defer.Deferred () 
    def close_command_is_queued(* args) : 
        return self._closing_deferred 
d = self.torstate.close_circuit (self.id, ** kw) 
    d.addCallback (<MASK>) 
    return self._closing_deferred 
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
def close_command_is_queued(