This has nothing to do with the article posted or anything, I was just curious... who gets to pick the animal on the book cover? Do you (the author) get to pick, or does the publisher (O'Reilly) pick?
For Go it had to be a Gopher (as it is the mascot for the language). My editor showed me the artwork and I approved it.
Do you mean the animal in general, or what specific image? For Go specifically, it would be very surprising if it was not a gopher! Ok, Python is obviously even more closely associated with the snake, but a gopher has been the Go mascot from the very beginning (the original design being drawn by the wife of one of the language's co-creators)...