using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

​

public class Program

{

}

​

public class AsyncQuerySet

{

    public List<Task<IEnumerable<int>[]>> EnumerableIds { get; set; }

    public List<Task<int[]>> ArrayIds { get; set; }

    public AsyncQuerySet()

    {

        this.EnumerableIds = new List<Task<IEnumerable<int>[]>>();

        this.ArrayIds = new List<Task<int[]>>();

    }

    public IEnumerable<int> Flatten()

    {

        return this.ArrayIds.SelectMany(w => w.Result).Distinct().Union(

            this.EnumerableIds.SelectMany(wc => wc.Result).SelectMany(x => x)

        );

    }

}