def check_balanced_brackets(bracket_str):
bracket_list = list(bracket_str)
bracket_stack = Stack()
for symbol in bracket_list:
if symbol in ['(', '{', '[']:
bracket_stack.push(symbol)
continue
elif symbol in [')', '}', ']']:
if not bracket_stack.is_empty() and pair_match(
symbol, bracket_stack.peak()):
bracket_stack.pop()
else:
return False
else:
raise Exception('Invalid symbol found')
return bracket_stack.is_empty()
def test_peak(self):
stack = Stack()
self.assertIsNone(stack.peak())
stack.push(5)
self.assertEqual(stack.peak(), 5)
self.assertEqual(len(stack), 1)
