From 6bde21f85c26708a5bbbe0926f7e752c5e76e106 Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Sat, 7 May 2022 15:38:17 +0200
Subject: [PATCH] fix(avl): be more explicit in `is_correct`

Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 avl.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/avl.py b/avl.py
index 5445168..eda3a63 100644
--- a/avl.py
+++ b/avl.py
@@ -29,7 +29,11 @@ class AVLTree(RankedTree[T]):
         if not node:
             return True
 
-        if not (-1 <= _balance_factor(node) <= 1):
+        if not (
+            -1 <= _balance_factor(node) <= 1
+            and node.rank
+            == 1 + max(Node.get_rank(node.left), Node.get_rank(node.right))
+        ):
             return False
 
         return not recursive or (