anchor.diff:     ;
   
   alternative
  -   : element +
  +   : element+
      ;
   
   exceptionGroup
  -   : (exceptionHandler) + (finallyClause)?
  +   : (exceptionHandler)+ (finallyClause)?
      | finallyClause
      ;
   
  
positive.code:    ;
  
  treeSpec
     : '^(' element (element) + ')'
     ;
  
  ebnf
  
negative.code:    ;
  
  optionsSpec
     : OPTIONS (option ';')+ '}'
     ;
  
  option
  