 Let's take another look at your big game. Last time, you animated the target and danger sprites to move across the screen, but when they left the screen they never came back. We're going to use booleans to bring them back to the screen, so they move across the screen repeatedly. In the last stage, you learned how to keep Sam the bat from leaving his backyard by using a boolean to check if he was safe left and safe right. Now you're going to add the same functionality to your video game. Each time your target and danger moves, the video game engine will send their X coordinate to the on-screen function. If on-screen never returns false, that means the sprite has gone off the screen, and the engine will take care of resetting it to the opposite side. Just like you did with Sam the bat, you'll want to first complete the safe left and safe right functions before combining them both in on-screen.