ChangeOil is an awful example. Your “better” code is untestable. And ChangeOil(car, nil) makes complete sense to remove all the car’s oil: in Go, a nil slice i

ChangeOil is an awful example. Your “better” code is untestable. And ChangeOil(car, nil) makes complete sense to remove all the car’s oil: in Go, a nil slice is (essentially) equivalent to [].