code: private void explain(final String message, final ParsedLine line) {
      // ParsedLine has no sane toString(); render all its details to logging
      log.trace("{}: line={}, words={}, word-index: {}, word-cursor: {}, cursor: {}",
        message,
        line.line(),
        line.words(),
        line.wordIndex(),
        line.wordCursor(),
        line.cursor()
      );
    }
docs: Helper to log {@link ParsedLine} details.