Simple Behaviour Tree experiments python

behaviour.py

class Tree:
    def __init__(self, root):
        self.root_node = root
        self.next_node = self.root_node

    def tick(self):
        print("next node is: {}".format(self.next_node))
        if self.next_node is False: 
            #TODO: Replace with enum: 
            #       Continue, Success, Failure
            # TODO: Replace this with a stack so we can Pop()
            # and get back to the parent node easily.
            # tree failed, return to root.
            print("Failure, go back to root")
            self.next_node = self.root_node
        if not callable(self.next_node):
            raise RuntimeError("Node was not callable {}".format(self.next_node))

        # call current and it evaulates and returns a Node() or result.
        print("Get next node")
        self.next_node = self.next_node()


class Node:
    children = []

    def __init__(self, *children):
        self.children = (c for c in children)

    def __call__(self, *args, **kwargs):
        # override in children to add node() functionality
        pass


class Sequence(Node):
    children = []

    def __init__(self, *children):
        print("Setting sequence children to {}".format(children))
        super().__init__(*children)

    def __call__(self, *args):
        next_node = next(self.children, False)
        print("Sequence next is: {}".format(next_node))
        return next_node


class If(Node):
    def __init__(self, test, return_node):
        self.test_function = test
        self.return_node = return_node
        super().__init__()

    def __call__(self):
        if not callable(self.test_function):
            raise Exception("Cant test not callable object")
        print("Calling IF test function")
        if self.test_function():
            print("IF tested TRUE")
            return self.return_node

class Printer(Node):

    def __call__(self, *args, **kwargs):
        print("I was called {}".format(self))


def testo():
    return True



ai = Tree(root=If(testo, Sequence(
    Printer(),
    Printer(),
    Printer()
)))

ai.tick()
ai.tick()
ai.tick()