s2d = function (str) {
	        return str < 10 ? ('0' + str) : str;
	    }
ISO Date format
@param {string} tpl
@param {number} value
@param {boolean} [isUTC=false] Default in local time.
          see `module:echarts/scale/Time`
          and `module:echarts/util/number#parseDate`.
@inner