Not entirely mine but beautiful nonetheless:

    @dataclass
    class Node:
        id: str
        children: List[Node] = field(default_factory=list)

        # beautiful Python: traverse a tree depth-first, pre-order (stack based)
        def __iter__(self):
            stack = [self]
            while stack:
                node = stack.pop()
                yield node
                stack = node.children + stack