PyCS/pycs/observable/Observable.py

class Observable:
    @staticmethod
    def create(source, parent=None):
        from . import ObservableDict
        from . import ObservableList

        if isinstance(source, dict):
            return ObservableDict(source, parent)
        if isinstance(source, list):
            return ObservableList(source, parent)
        else:
            return source

    def __init__(self, parent):
        self.__parent = parent
        self.__subscriptions = []

    def subscribe(self, handler, immediate=False):
        self.__subscriptions.append(handler)

        if immediate:
            handler(self)

    def _notify(self):
        for s in self.__subscriptions:
            s(self)

        if self.__parent is not None:
            self.__parent._notify()