anchor.diff:   * to be a column delimiter.
    */
   private boolean isElementSeparator() {
  -    if(!(notInBrackets() || inCurly() || inSquare())) {
  +    if(!(inCurly() || inSquare())) {
           return false;
       }
       Token prevToken = input.LT(-1);
  
positive.code: //non-empty
  element_separator_list :
       t_FILLER? t_COMMA t_FILLER? //just echo
    |  element_separator_filler //insert comma
    ;
  
  element_separator_filler :
       {isElementSeparator()}? { offsetTracker.recordOffsetChange(0, -1); offsetTracker.advanceInLine(1); } t_FILLER -> template(filler={$text}) ",<filler>" //insert comma
    ;
  
  //non-empty
  
negative.code: private boolean inParens() { return !bracketStack.isEmpty() && bracketStack.peek() == LPAREN; }
  private boolean inCurly() { return !bracketStack.isEmpty() && bracketStack.peek() == LCURLY; }
  private boolean inSquare() { return !bracketStack.isEmpty() && bracketStack.peek() == LSQUARE; }
  }
  
  @lexer::header {
  