code: public Duration dividedBy(long divisor, RoundingMode roundingMode) {
          if (divisor == 1) {
              return this;
          }
          return new Duration(FieldUtils.safeDivide(getMillis(), divisor, roundingMode));
      }
docs: Returns a new duration with its length divided by the
  specified divisor. {@code RoundingMode} can be specified.
  This instance is immutable and is not altered.
  <p>
  If the divisor is one, this instance is returned.
  
  @param divisor  the divisor to divide this one by
  @param roundingMode  the type of rounding desired
  @return the new duration instance