function fmtLong(ms) {
	  return plural(ms, d, 'day') ||
	    plural(ms, h, 'hour') ||
	    plural(ms, m, 'minute') ||
	    plural(ms, s, 'second') ||
	    ms + ' ms';
	}
Set max-age to `maxAge`.

@param {Number} maxAge
@return {SendStream}
@api public