_dateToISO(date) {
      if (date && (date instanceof Date)) {
         date = date.toISOString();
      }

      return date;
   }
if a `Date` is passed to this function it will be converted to an ISO string
@param {*} date - the object to attempt to coerce into an ISO date string
@return {string} - the ISO representation of `date` or whatever was passed in if it was not a date