using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var list = Get();

        foreach(var item in list)

        {

            Console.WriteLine(item.IsSomething);    

        }

    }

    public static IEnumerable<Test> Get()

    {

        var numbers = new [] 

        { 

            new Test { IsSomething = true },

            new Test { IsSomething = true },

            new Test { IsSomething = true },

            new Test { IsSomething = true }

        };

        var list = numbers.Where(n => n.IsSomething);

        foreach(var item in list)

        {

            item.IsSomething = false;

        }

        return list;

    }

    public class Test

    {

        public bool IsSomething {get; set;} 

    }

}