def walk(self, callback, collect=None):
        if collect is None:
            collect = []

        r = callback(self)
        if r is not None:
            collect.append(r)

        for node in self.get_children():
            node.walk(callback, collect)

        return collect
Executes callback on all the subtree starting at self.
dataset/ETHPy150Open los-cocos/cocos/cocos/cocosnode.py/CocosNode.walk