What version of Go are you using (go version)?

https://tour.golang.org/moretypes/18

What did you expect to see?

In exercise-slices.go on the page https://tour.golang.org/moretypes/18 it would be helpful to explain that in the main function, in the call to pic.Show(Pic) that Pic is a function value being passed to the Show method. At this point in the tutorial we are not exposed to "Function values" yet. I had a difficult time trying to figure out what the values being passed to the Pic function were. With some print statements I saw that the values of dx and dy where both 256. Only when I got to the "Function values" section of the tour did I get it that it was function value being based to Show. I found the code for pic.go and now get how the parameters of Show, dx and dy, get default values of 256. https://github.com/golang/tour/blob/master/pic/pic.go#L27

For those of us new to Go, that can be very confusing.