Serializable 構造体は乱数生成器の完全な内部状況を把握するために使用されます。関連項目: Random.state.
This is an opaque data structure intended for serialization (save and restore) purposes only. Its fields are all private and
have no useful meaning on their own outside of the algorithm. A seed set with InitState, for example, cannot be
retrieved after even a single iteration of the generator.
See Random for details on the algorithm.