human
Solve the following python programming problem given the following code:
@ defer.inlineCallbacks 
def user_syncing(self, user_id, affect_presence = True) : 
    "Returns a context manager that should surround any stream requests
        from the user.

        This allows us to keep track of who is currently streaming and who isn't
        without having to have timers outside of this module to avoid flickering
        when users disconnect/reconnect.

        Args:
            user_id (str)
            affect_presence (bool): If false this function will be a no-op.
                Useful for streams that are not associated with an actual
                client that is being used by a user.
        " 
    if curr_sync : 
        curr_sync = self.user_to_num_current_syncs.get (user_id, 0) 
        self.user_to_num_current_syncs [user_id] = (curr_sync + 1) 
        prev_state = (yield self.current_state_for_user (user_id)) 
        if (prev_state.state == PresenceState.OFFLINE) : 
            (yield self._update_states ([prev_state.copy_and_replace (state = PresenceState.ONLINE, last_active_ts = self.clock.time_msec (), last_user_sync_ts = self.clock.time_msec ())])) 
else : 
            (yield self._update_states ([prev_state.copy_and_replace (last_user_sync_ts = self.clock.time_msec ())])) 
@ defer.inlineCallbacks 
    def _end() : 
        if affect_presence : 
            self.user_to_num_current_syncs [user_id] -= 1 
            prev_state = (yield self.current_state_for_user (user_id)) 
            (yield self._update_states ([prev_state.copy_and_replace (last_user_sync_ts = self.clock.time_msec ())])) 
@ contextmanager 
    def _user_syncing() : 
        try : 
            (yield) 
finally : 
            preserve_fn (_end) () 
defer.returnValue (_user_syncing ()) 

    
    

    Fix the buggy line: if curr_sync :
assistant
#Here is Python program to fix the buggy line: if curr_sync :
.

if affect_presence :