Balance parentheses

bp.py

OPEN_BRACKETS = '[{('
CLOSING_BRACKETS = ']})'


def is_matching(open_bracket: str, close_bracket: str) -> bool:
    return OPEN_BRACKETS.index(open_bracket) == \
           CLOSING_BRACKETS.index(close_bracket)


def is_balanced(input_string: str) -> bool:
    # String should have at least one bracket
    if not any([bracket in input_string for bracket in OPEN_BRACKETS]):
        return False

    stack = []
    for char in input_string:
        if char in OPEN_BRACKETS:
            stack.append(char)
        elif char in CLOSING_BRACKETS:
            matching_open = stack.pop() if stack else ''
            if not is_matching(matching_open, char):
                return False
    # Stack should be empty if all brackets matched
    return not stack


class Solution(object):
    def __call__(self, *args, **kwargs):
        # Positive cases
        assert is_balanced('(a[0]+b[2c[6]]) {24 + 53}') is True
        assert is_balanced('f(e(d))') is True
        assert is_balanced('[()]{}([])') is True

        # Negative cases
        assert is_balanced('((b)') is False
        assert is_balanced('(c]') is False
        assert is_balanced('{(a[])') is False
        assert is_balanced('([)]') is False
        assert is_balanced(')(') is False

        # Corner cases
        assert is_balanced('') is False
        assert is_balanced('without brackets') is False


s = Solution()
s()  # check