check_string.py

def check_string(s):
    mstack = []
    bFind = False
    matches = {')': '(', '}': '{', ']': '['}
    for c in s:
        if c in matches.values():
            bFind = True
            mstack.append(c)
        elif c in matches.keys():
            if len(mstack) == 0 or mstack[-1] != matches[c]:
                return False
            mstack.pop()
        else:
            print("unexpected character")
            return False
    return bFind and len(mstack) == 0