namespace TestConsole
{
    using System;
    using System.Collections;
    using System.Collections.Generic;

    public class Collection
    {
        private Dictionary<Type, IList> _dict;

        public Collection()
        {
            _dict = new Dictionary<Type, IList>();
        }

        public void Add<T>(T item)
            where T : IKek
        {
            var list = GetList<T>();
            list.Add(item);
        }

        public List<T> GetList<T>()
            where T : IKek
        {
            if (_dict.TryGetValue(typeof(T), out var list))
            {
                return list as List<T>;
            }

            var newList = new List<T>();
            _dict.Add(typeof(T), newList);
            return newList;
        }
    }

    public interface IKek
    {
    }
}