evalRPN = function (tokens, stack = []) {
    for (const char of tokens) {/* Time O(N) */
        const isOperation = char in OPERATORS;
        if (isOperation) {
            const value = performOperation(char, stack);

            stack.push(value);      /* Space O(N) */

            continue;
        }

        stack.push(Number(char));   /* Space O(N) */
    }

    return stack.pop();
}
https://leetcode.com/problems/evaluate-reverse-polish-notation
Time O(N) | Space(N)
@param {string[]} tokens
@return {number}