static const Dict brackets = {'{': '}', '[': ']', '(': ')'};
static const Set all_brackets = {'{','}','[',']','(',')'};

bool checkBrackets(String s) {
    Stack stack;
    foreach (char c in s) {
        if (c in all_brackets) {
            if (c in brackets.keys()) {
                stack.push(s);
            } else if (stack.empty()) {
                return false;
            } else if (brackets[stack.peek()] != c) {
                return false;
            } else {
                stack.pop();
            }
        }
    }
    return (stack.empty())
}