function pad(n, l, char) {
        if (char === void 0) { char = '0'; }
        var str = '' + n;
        var r = [str];
        for (var i = str.length; i < l; i++) {
            r.push(char);
        }
        return r.reverse().join('');
    }
@returns the provided number with the given number of preceding zeros.