using System;

using System.Collections.Generic;

public class Entry {

    public void postDate(){}

}

​

public class TransactionBundle {

    public ListManager ListManager { get; set; } = new ListManager();

    public void postDate(){}

}

​

public class ListManager {

    List<Entry> internalEntries = new List<Entry>();

    public void add(List<Entry> entries){

        internalEntries.AddRange(entries);

    }

    public bool hasEntry(Entry entry) {

        return internalEntries.Contains(entry);

    }

}

​

public class TransactionGate

{   

    TransactionBundle transactionBundle = new TransactionBundle();

    public void postEntries(List<Entry> entries) {

        foreach (var entry in entries) {

            entry.postDate();

        }

        transactionBundle.ListManager.add(entries);

    }

    List<Entry> uniqueEntries(List<Entry> entries) {

        List<Entry> result = new List<Entry>();

        foreach(var entry in entries) {

            if (!transactionBundle.ListManager.hasEntry(entry)) {

                result.Add(entry);

            }

        }

        return result;

    }

}

​

public class Program

{

    public static void Main()

    {

​

    }

}