code: public void printTo(Writer out, ReadablePeriod period) throws IOException {
          checkPrinter();
          checkPeriod(period);
          
          getPrinter().printTo(out, period, iLocale);
      }
docs: Prints a ReadablePeriod to a Writer.
  
  @param out  the formatted period is written out
  @param period  the period to format, not null