code: public String outputString(final SyndFeed feed, final boolean prettyPrint) throws FeedException {
          return feedOutput.outputString(feed.createWireFeed(), prettyPrint);
      }
docs: Creates a String with the XML representation for the given SyndFeedImpl.
  <p>
  If the feed encoding is not NULL, it will be used in the XML prolog encoding attribute. It is
  the responsibility of the developer to ensure that if the String is written to a character
  stream the stream charset is the same as the feed encoding property.
  <p>
  
  @param feed Abstract feed to create XML representation from. The type of the SyndFeedImpl
  must match the type given to the FeedOuptut constructor.
  @param prettyPrint pretty-print XML (true) oder collapsed
  @return a String with the XML representation for the given SyndFeedImpl.
  @throws FeedException thrown if the XML representation for the feed could not be created.