q of type Query. So in the function you can access the fields on q (Where you call the function on) via q.FieldName. If you do it with a pointer receiver (q *Qu

q of type Query. So in the function you can access the fields on q (Where you call the function on) via q.FieldName. If you do it with a pointer receiver (q *Query) like explained here (https://tour.golang.org/methods/4 https://tour.golang.org/methods/4) you can directly manipulate the object, not the copy like in this example.