anchor.diff:      transformVars.sort();
     }
   
  -  void SetBodyWithMain(List<String> body, {List<String> prolog = null}) {
  +  void SetBodyWithMain(List<String> body, {List<String> prolog}) {
       assert(shader == null);
       shader = _CreateShader(true, body, prolog);
     }
   
  -  void SetBody(List<String> body, {List<String> prolog = null}) {
  +  void SetBody(List<String> body, {List<String> prolog}) {
       assert(shader == null);
       shader = _CreateShader(false, body, prolog);
     }
  
positive.code:       out.add("}");
      }
  
      //print (out.join("\n"));
      return out.join("\n");
    }
  }
  
negative.code:     assert(shader == null);
  
      for (String n in names) {
        assert(_VarsDb.containsKey(n), "missing uniform $n");
        assert(!uniformVars.contains(n));
        uniformVars.add(n);
      }
  