fix export

Author: eyas-ranjous

index.js

@@ -1,7 +1,7 @@
 const { BinarySearchTreeNode } = require('./src/binarySearchTreeNode');
 const { AvlTreeNode } = require('./src/avlTreeNode');
-const BinarySearchTree = require('./src/binarySearchTree');
-const AvlTree = require('./src/avlTree');
+const { BinarySearchTree } = require('./src/binarySearchTree');
+const { AvlTree } = require('./src/avlTree');
 
 module.exports = {
   BinarySearchTreeNode,