test Godot custom iterators

node_walk.gd

class_name NodeWalk
extends StackIterator

func _init(node).(node):
	pass

func _iter_(current):
	for i in current.get_children():
		stack.push_back(i)

stack_iterator.gd

class_name StackIterator

var stack = []
var current

func _init(node:Node):
	stack.append(node)

func _iter():
	current = stack.pop_back()
	if current == null:
		return false
	_iter_(current)
	return true

# override it
func _iter_(current):
	pass

func _iter_init(_arg):
	return _iter()

func _iter_next(_arg):
	return _iter()

func _iter_get(_arg):
	return current

Questions:

1. What is _arg for?
2. Why I need to write this weird thing in NodeWalk:

func _init(node).(node):
	pass

answers:

1. ?
2. If a class requires a constructor param, then the extending classes must explicitly declare what to pass to it