anchor.diff:      arg.d += 1;
       arg.n += 1;
       arg.b = true;
  +    arg.s = arg.s + " no more!";
       arg.l.add(4);
       arg.m['four'] = 4;
     }
  
positive.code:     modifyOne(arg.d);
      modifyOne(arg.n);
      modifyOne(arg.b);
      modifyOne(arg.l);
      modifyOne(arg.m);
    }
  
negative.code:   double d = 1.0;
    num n = 1;
    bool b = false;
    String s = "Pretty String";
    List l = [1, 2, 3];
    Map m = { 'one' : 1, 'two' : 2, 'three' : 3 };
    
    String toString() => 'Values: $i, $d, $n, $b, $s, $l, $m';
    
  }
  
  