I think there are some obvious mistakes in it: 1) The NewXXX() function should return a pointer by Go idioms. But they return the value in this article. 2) For

I think there are some obvious mistakes in it: 1) The NewXXX() function should return a pointer by Go idioms. But they return the value in this article. 2) For methods on IntSet type, it says the receiver should be pointer instead of value. "If we used values, these would be copied and any changes applied lost." Actually, since the data field is a reference, using value as receiver can change the content of the map. Maybe not a good tutorial for people new to Go.