在二叉树python结构中创建根节点

Question

class Tree:
    class Node:
        def __init__(self, left=None, right=None, parent=None, element=None):
            self.left = left
            self.right = right
            self.parent = parent
            self.element = element

    class Position:
        def make_position(self, node):
            def __init__(self):
                """Create an initially empty binary tree."""
                self.root = None
                self.size = 0

            def root(self):
                """Return the root Position of the tree( or None if tree is empty)."""
                return self.make_position(self.root)

            def add_root(self, e):
                """Place element e at the root of an empty tree and return new Position.
                Raise ValueError if tree nonempty."""
                if self.root is not None:
                    raise ValueError("Root Exist")
                self.size = 1
                self.root = self.Node(e)
                return self.make_position(self.root)

  

我是python和python数据结构的初学者。   如何在文件.py的末尾调用add_root方法并打印此方法以查看根节点中的元素？   我试图写

root = Tree.Position()
print(root.make_position(root))
root = Tree.Position.make_position()
print(root.make_position(root))

但是解释器返回AttributeError