public void addDocument(Document doc) throws IOException {
		// needs to differenciate SimpleDocuments from MultiField ones
		// each class has its own way of serializing
		String serial = doc.getStringSerialization();
		raw_file_buffer.write(serial);
	}
public void addDocument ( Document doc ) throws IOException { String serial = doc . getStringSerialization ( ) ; raw_file_buffer . write ( serial ) ; }
there is exactly one document per line