def detach(self, observer):
        """
        Detach an observer from this Observable.

        @param observer: The Observer to detach.
        @type observer: Observer
        """
        try:
            self._observers.remove(observer)
        except KeyError:
            pass

        Detach an observer from this Observable.

        @param observer: The Observer to detach.
        @type observer: Observer
        
pypattyrn/behavioral/observer.py