anchor.diff:     (
         IP
         | IPV6
  -   ) PREFIX_LIST name = ~NEWLINE NEWLINE ip_prefix_list_tail*
  +   ) PREFIX_LIST name = variable NEWLINE ip_prefix_list_tail*
   ;
   
   null_as_path_regex
  
positive.code:    {
  		$again = (_input.LT(1).getType() == IP || _input.LT(1).getType() == IPV6) &&
  		_input.LT(2).getType() == PREFIX_LIST &&
  		_input.LT(3).getType() == VARIABLE &&
  		_input.LT(3).getText().equals($name.text);
  	}
  
  
negative.code:    (
        IP
        | IPV6
     ) PREFIX_LIST name = ~NEWLINE
     (
        ip_prefix_list_tail
        | ip_prefix_list_null_tail
  