遇到super()问题

我有两个单继承类,旨在作为一个简单的树实现:

class tree:
    def __init__(self, nodes = set()):
        self.nodes = nodes

    def addnode(self, node):
        self.nodes.add(node)

class Node(tree):
    def __init__(self, name = '1', data = None, children = set()):
        self.data = data
        self.children = children
        self.name = name
    
        super().addnode(self)

tree()
Node('1')

但是,运行此代码会返回错误:

    self.nodes.add(node)
    ^^^^^^^^^^
AttributeError: 'Node' object has no attribute 'nodes'

我找不到任何资源来回答这个具体问题。有人能帮帮我吗?