sharp-chat/SharpChat/IServerPacket.cs

namespace SharpChat {
    public abstract class ServerPacket {
        public long SequenceId { get; }

        public ServerPacket(long sequenceId = 0) {
            // Allow sequence id to be manually set for potential message repeats
            SequenceId = sequenceId > 0 ? sequenceId : SharpId.Next();
        }

        public abstract string Pack();
    }
}