二叉搜索树插入

def solve():
    class TreeNode:
        def __init__(____):
            self.val = val
            self.left = None
            self.right = None
    def insert(____):
        if root is None:
            return TreeNode(____)
        if val < root.val:
            root.left = insert(____)
        else:
            root.right = insert(____)
        return root
    root = None
    for v in [____, ____, ____, ____, ____]:
        root = insert(____)
    result = []
    def inorder(____):
        if node:
            inorder(____)
            result.append(str(____))
            inorder(____)
    inorder(____)
    print('____'.join(____))