def test_identifies_valid_sequence(self):
self.assertTrue(is_balanced('()'))
self.assertTrue(is_balanced('()(())'))
self.assertTrue(is_balanced('{{([][])}()}'))
def test_identifies_right_imbalance(self):
self.assertFalse(is_balanced('())'))
def test_identifies_mismatch(self):
self.assertFalse(is_balanced('{[])'))
def test_identifies_left_imbalance(self):
self.assertFalse(is_balanced('(()'))
