code: public static Expression dateAddStr(Expression expression, int n, DatePart part) {
          return x("DATE_ADD_STR(" + expression.toString() + ", " + n + ", \"" + part + "\")");
      }
docs: Returned expression results in Performs Date arithmetic. n and part are used to define an interval or duration,
  which is then added (or subtracted) to the date string in a supported format, returning the result.