树遍历“打印代码”可以返回吗？

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def print_tree(root):
    if root is None:
        return
    
    # 打印当前节点的值
    print(root.val)
    
    # 递归遍历左子树
    print_tree(root.left)
    
    # 递归遍历右子树
    print_tree(root.right)

# 创建一个示例树
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(4)
root.left.right = TreeNode(5)

# 执行树遍历打印代码
print_tree(root)

1
2
4
5
3