code: public static void writeln(final Writer writer, final String string, int indentLevel) throws IOException {
          writer.write(StringUtils.repeat("\t", indentLevel) + string);
          writer.write("\n");
      }
docs: Write out the string and a newline, appending a number of tabs to
  properly indent the resulting text-file.
  
  @param writer The writer for the .dot-file
  @param string The text to write
  @param indentLevel How much to indent the line
  @throws IOException if writing to the Writer fails