timestamp = function (date, separator) {
        // use the iso string to ensure left padding and other stuff is taken care of
        return (date || new Date()).toISOString().replace(/[^\d]+/g, _.isString(separator) ? separator : TS_SEP);
    }
Generate a timestamp from date

@param {Date=} date - The timestamp used to mark the exported file.
@param {String=} separator - The optional string with which to separate different sections of the timestamp,
defaults to TS_SEP
@returns {String} - yyyy-mm-dd-HH-MM-SS-MS-0