在python中创建带有子级的递归类树

class TreeNode:
    def __init__(self, value):
        self.value = value
        self.children = []

    def add_child(self, child_node):
        self.children.append(child_node)

    def __repr__(self, level=0):
        ret = "\t" * level + repr(self.value) + "\n"
        for child in self.children:
            ret += child.__repr__(level + 1)
        return ret

def print_tree(node, level=0):
    if node is None:
        return
    print("\t" * level + str(node.value))
    for child in node.children:
        print_tree(child, level + 1)

from collections import deque

def print_tree_iterative(root):
    if not root:
        return
    queue = deque([root])
    while queue:
        node = queue.popleft()
        print(node.value)
        queue.extend(node.children)