AVL树是自平衡二叉搜索树，通过旋转来保持树的平衡。平衡因子是左子树高度减去右子树高度的差，当平衡因子的绝对值大于1时，需要进行旋转操作来使树重新保持平衡。 以下是一个示例代码，实现了AVL树中的插入和删除操作，并通过旋转实现了平衡维护。

class AVLTree:
    class Node:
        def __init__(self, val):
            self.val = val
            self.height = 1
            self.left = None
            self.right = None
            
    def __init__(self):
        self.root = None
        
    def height(self, node):
        if node is None:
            return 0
        return node.height

    def balance_factor(self, node):
        if node is None:
            return 0
        return self.height(node.left) - self.height(node.right)

    def left_rotate(self, node):
        right_child = node.right
        node.right = right_child.left
        right_child.left = node

        node.height = 1 + max(self.height(node.left), self.height(node.right))
        right_child.height = 1 + max(self.height(right_child.left), self.height(right_child.right))

        return right_child

    def right_rotate(self, node):
        left_child = node.left
        node.left = left_child.right
        left_child.right = node

        node.height = 1 + max(self.height(node.left), self.height(node.right))
        left_child.height = 1 + max(self.height(left_child.left), self.height(left_child.right))

        return left_child

    def insert(self, node, val):
        if node is None:
            return self.Node(val)

        if val < node.val:
            node.left = self.insert(node.left, val)
        elif val > node.val:
            node.right = self.insert(node.right, val)

        node.height = 1 + max(self.height(node.left), self.height(node.right))
        balance_factor = self.balance_factor(node)

        if balance_factor > 1: