code: public static Expression dateDiffStr(Expression expression1, Expression expression2, DatePart part) {
          return x("DATE_DIFF_STR(" + expression1.toString() + ", " + expression2.toString()
                  + ", \"" + part.toString() + "\")");
      }
docs: Returned expression results in Performs Date arithmetic.
  Returns the elapsed time between two date strings in a supported format, as an integer whose unit is part.