docs: function format(date, month, time) {
    return date.getFullYear() +
           zeroFill(date.getMonth() + 1) +
           (month ? zeroFill(date.getDate()) : '') +
           (time ?  'T' + zeroFill(date.getHours()) + zeroFill(date.getMinutes()) +
              zeroFill(date.getSeconds()) + 'Z' : '');
  }