IN PYTHON PLEASE :)

class Stream (object): def init (self, first, compute rest, empty- False): self. first = first self-compute-rest = compute-rest self.empty -empty self. rest None self. ._computed-False @property def rest(self) assert not self.empty, if not self. computed: "Empty streams have no rest self. rest - self. compute rest () self. com puted = True return self. rest empty_stream - Stream (None, None, True) class Stream (object): def init (self, first, compute rest, empty- False): self. first = first self-compute-rest = compute-rest self.empty -empty self. rest None self. ._computed-False @property def rest(self) assert not self.empty, if not self. computed: "Empty streams have no rest self. rest - self. compute rest () self. com puted = True return self. rest empty_stream - Stream (None, None, True)