anchor.diff:    Variable;
     ArrayEnd;
     Index;
  +  UnaryMinus;
   }
   
   program
  
positive.code: 
  expr_cast
    : expr_incdec
    | NEG expr_incdec
    | MINUS expr_incdec
    ;
  
  expr_incdec
  
negative.code:   ;
  
  fact
    : NOT^ fact
    | expr_instanceof
    ;
  
  