function getLeadingWhitespace(str, start, end) {
        if (start === void 0) { start = 0; }
        if (end === void 0) { end = str.length; }
        for (var i = start; i < end; i++) {
            var chCode = str.charCodeAt(i);
            if (chCode !== 32 /* Space */ && chCode !== 9 /* Tab */) {
                return str.substring(start, i);
            }
        }
        return str.substring(start, end);
    }
Returns the leading whitespace of the string.
If the string contains only whitespaces, returns entire string