code: public static void write(final GPX gpx, final OutputStream output)
  		throws IOException
  	{
  		writer().write(gpx, output);
  	}
docs: Writes the given {@code gpx} object (in GPX XML format) to the given
  {@code output} stream.
  
  @param gpx the GPX object to write to the output
  @param output the output stream where the GPX object is written to
  @throws IOException if the writing of the GPX object fails
  @throws NullPointerException if one of the given arguments is {@code null}