Adjust location of game definition in "Collections"

[k4y3ff]

In collections.clj, some of the exercises refer to game, which is shown as being def'd earlier in the text.

However, game has not been defined unless the attendees intentionally went back and eval'd that segment when they were reading it. As a result, some of the exercises make it seem like the function solutions should take three parameters instead of two--or something similar--because the error messages make it unclear that game should be globally defined.

tl;dr Either adjust the exercises to take game as a parameter, move the game definition into the same place as the exercises, or something else vaguely.