any resource allocated by the Bela backend is already taken care of. cleanup() is to give the user a chance to release memory and resources they allocated in setup(). For instance, if you call open() on a file descriptor in setup(), and read() and/or write() to it from render(), you will want to call close() it in cleanup(). Most Bela examples don't allocate any resources or memory in setup() and therefore do not need to release them in cleanup().
