def test_delete_node(self):
if __print__:
print('test_delete_node >>>>')
bst = AVL().from_list(self.bst_data)
if __print__:
bst.print_tree()
bst.delete_node(bst.root.left)
if __print__:
bst.print_tree()
self.assertEqual(bst.length, len(self.bst_data) - 1)
if __print__:
print('<<<< test_delete_node')
