RandomGenerator class Null safety
Implementation of the RAN # key, and sto/rcl
Note that the generator isn't re-seeded with the last value every time a number is requested. That means that the sequence: STO RAN # RAN # STO RAN # RAN # will yield a different result than: STO RAN # RAN # RAN # whereas the two will generate identical results on a real 15C.
Re-seeding each time would presumably generate worse results that Dart's built-in function, and I'm a little concerned it might even lead to pathological cases, like small cycles in certain cases.