Ok i got it thank you for your answer.

Ok i got it thank you for your answer.

asterisks were added by copying the code in the text box. There is nothing wrong with the syntax. It's because of the unapply function. It seems that you cant use x,y it both unapply function. But i dont understand why ?

asterisks were added by copying the code in the text box. There is nothing wrong with the syntax. It's because of the unapply function. It seems that you cant use x,y it both unapply function. But i dont understand why ?