public static bool?GetBoolean(this ISession session, string key)
 => NullableValue.Map <byte[], bool>(session.Get(key), bytes => BitConverter.ToBoolean(bytes));
 public static int?GetInt32(this ISession session, string key)
 => NullableValue.Map <byte[], int>(session.Get(key), bytes => BitConverter.ToInt32(bytes));
 public static string?GetString(this ISession session, string key)
 => NullableValue.Map(session.Get(key), Encoding.UTF8.GetString);