Fix option A: use 'MotionKit.color_class', which returns a platform-specific class, and has shared code
even though this method usually doesn't get a block, wrappers (e.g. wrapping the 'on' method so that sugarcube's 'on' helper works) might need to send a block
updated documentation, and by moving 'block' out of create, we get one less method in a potentially *long* stack trace