class Example {

  private Example() {
  }

  /**
   * Create an example text (usually just one sentence) with an error - the error must be marked with {@code <marker>...</marker>}.
   * @throws IllegalArgumentException if the {@code <marker>...</marker>} is missing
   * @since 2.5
   */
  public static IncorrectExample wrong(String example) {
    requireMarkup(example);
    return new IncorrectExample(example);
  }

  /**
   * Create an example text (usually just one sentence) without an error - the fixed error (compared to the text created
   * with {@link #wrong(String)}) can be marked with {@code <marker>...</marker>}.
   * @since 2.5, return type modified in 3.5
   */
  public static CorrectExample fixed(String example) {
    return new CorrectExample(example);
  }

  private static void requireMarkup(String example) {<FILL_FUNCTION_BODY>}

}

    if (!example.contains("<marker>") || !example.contains("</marker>")) {
      throw new IllegalArgumentException("Example text must contain '<marker>...</marker>': " + example);
    }
  
<no_super_class>