anchor.diff:      if (args == null) {
         return null;
       }
  -    return new FSArguments(sap, args);
  +    return new _FSArguments(sap, args);
   
     });
   
  
positive.code:   if (cf == null) {
      return null;
    }
    return new FSFunctionCompositeFunction(cf, c);
  
  });
  
  
negative.code:     return null;
    }
  
    return new _FSArgumentFunction(n, args);
  
  
  }
  