using System;

using System.Collections.Generic;

using System.Linq;

using System.Reflection;

public class Program

{

    public enum Allowed {

        SeqNum,

        CmdRes,

        Data,

        Checksum

    }

    public class AllowedCharsBase {

        public AllowedCharsBase() { }

        public virtual List<byte> GetBytes(ICollection<byte> bytes) {

            return (List<byte>)bytes;

        }

    }

    public class SeqNumber : AllowedCharsBase {

        public SeqNumber() { }

        public override List<byte> GetBytes(ICollection<byte> bytes) {

            return bytes.Skip(1).Take(1).ToList<byte>();

        }

    }

    class CommdResp : AllowedCharsBase {

        public CommdResp() { }

        public override List<byte> GetBytes(ICollection<byte> bytes) {

            return bytes.Skip(2).Take(1).ToList();

        }

    }

    class DataBlock : AllowedCharsBase {

        public DataBlock() { }

        public override List<byte> GetBytes(ICollection<byte> bytes) {

            var part = bytes.Skip(3).TakeWhile(b => b != 3).ToList();

            return part.GetRange(0, part.Count() - 2);

        }

    }

    class Checksum : AllowedCharsBase {

        public Checksum() { }

        public override List<byte> GetBytes(ICollection<byte> bytes) {

            return bytes.ToList().GetRange(bytes.Count() - 3, 2);

        }

    }

    public static void cout(string s) { Console.WriteLine(s); }

    public static void Main()

    {

        var data = new List<byte> { 0x02, 0x31, 0x85, 0x31, 0x32, 0x33, 0x47, 0x31, 0x03 };

        var block = Get<SeqNumber>(data);

        //string s = "";

        //foreach (var b in block) s += $"{b:X2} ";

        //Console.WriteLine($"Hello Bytes: {s}");

    }

    private static List<byte> Get<T>(ICollection<byte> bytes)

        where T : AllowedCharsBase

    {

        var c = new AllowedCharsBase() as T;

        if (c == null)

            cout("c is null");

        if (c is SeqNumber)

            cout("seq number");

​

        var ret = new List<byte>();

        if (c != null)

            ret = c.GetBytes(bytes);

        return ret;

    }

}