anchor.diff:    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 };
     SideEffect se = new SideEffect();
  
positive.code:     modifyOne(arg.d);
      modifyOne(arg.n);
      modifyOne(arg.b);
      modifyOne(arg.l);
      modifyOne(arg.m);
    }
  
negative.code:   
    testFunction(b, addOne); // No Side effects
    
    testFunction(s, addOne); // No Side effects
    testFunction(s, modifyOne); // No Side effects
    
    testFunction(l, addOne); // Side effect!
    testFunction(l, modifyOne); // Side effect!
    testFunction(l[1], addOne); // No side effect
  