code: public final void output(final Calendar calendar, final Writer out)
              throws IOException, ValidationException {
          if (isValidating()) {
              calendar.validate();
          }
  
          try (FoldingWriter writer = new FoldingWriter(out, foldLength)) {
              writer.write(calendar.toString());
          }
      }
docs: Outputs an iCalender string to the specified writer.
  @param calendar calendar to write to writer
  @param out a writer
  @throws IOException thrown when unable to write to writer
  @throws ValidationException where calendar validation fails