See the comment on the package object about using an implicit class.

Also, looking through the code for .saveAsHadoopFile in the spark codebase, I'm not sure if having the K and V be implicitly viewable as TileIdWritable and ArgWritable will have effect on process...I'm trying to figure out what the <% gives us, is it just the type safety of the call? Would this code work with any RDD[(K,V)]? If so, I could see the implicit class in the package having them for type safety, but this function not having them, and maybe be renamed to make users aware that it's more general than just saving what we're now calling 'Images' (although like I mentioned I think we should think about that name more). Also maybe it's worth constricting it to only RDD[(TileIdWritable,ArgWritable)] and having a type alias to improve code readability? Curios about your thoughts on this.