anchor.diff:      ;
   
   annotation
  -    : declarationModifier | userAnnotation
  +    : declarationModifier -> ^(ANNOTATION declarationModifier) 
  +    | userAnnotation
       ;
   
   //TODO: we could minimize backtracking by limiting the 
  
positive.code: grammar ceylon;
  
  options {
      //backtrack=true;
  
negative.code: //the annotation
  userAnnotation 
      : annotationName annotationArguments?
      -> ^(ANNOTATION annotationName annotationArguments?)
      ;
  
  annotationArguments
  