code: func extractBoolTagOrDie(key string, lines []string) bool {
  	val, err := types.ExtractSingleBoolCommentTag("+", key, false, lines)
  	if err != nil {
  		klog.Fatal(err)
  	}
  	return val
  }
docs: // extractBoolTagOrDie gets the comment-tags for the key and asserts that, if
  // it exists, the value is boolean.  If the tag did not exist, it returns
  // false.