public static function isComment($include_doc_comment = TRUE) {
    if ($include_doc_comment) {
      return function ($node) {
        if ($node instanceof LineCommentBlockNode) {
          return TRUE;
        }
        elseif ($node instanceof CommentNode) {
          return !($node->parent() instanceof LineCommentBlockNode);
        }
        else {
          return FALSE;
        }
      };
    }
    else {
      return function ($node) {
        if ($node instanceof LineCommentBlockNode) {
          return TRUE;
        }
        elseif ($node instanceof DocCommentNode) {
          return FALSE;
        }
        elseif ($node instanceof CommentNode) {
          return !($node->parent() instanceof LineCommentBlockNode);
        }
        else {
          return FALSE;
        }
      };
    }
  }