using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;

    class Program
    {
        static void Main(string[] args)
        {
            //Test with classes
            string[] classesList1 = new[] {"a", "b", "c"};
            string[] classesList2 = new[] { "1", "2", "3" };
            List<string[]> classesListCombined = new List<string[]> { classesList1, classesList2 };

            Console.WriteLine("classesList1: {0}", classesList1.Join());
            Console.WriteLine("classesListCombined: {0}", classesList1.Join());

            //Test with structs
            int[] structList1 = new[] { 1, 2, 3 };
            int[] structList2 = new[] { 4, 5, 6 };
            List<int[]> structListCombined = new List<int[]> { structList1, structList2 };


            Console.WriteLine("structList1: {0}", structList1.Join());
            Console.WriteLine("structListCombined: {0}", structListCombined.Join());

            //Test tripple nesting

            var nest1 = new[] {1, 2, 3};
            var nest2 = new[] { 4, 5, 6 };
            var nest3 = new[] { 7, 8, 9 };
            var nest4 = new[] {10, 11, 12};

            var layer1 = new[] {nest1, nest2};
            var layer2 = new[] {nest3, nest4};
            var top = new[] {layer1, layer2};


            Console.WriteLine("top: {0}", top.Join());

            Console.ReadLine();

        }
    }

    internal static class ExtensionMethods
    {
        public static String Join<T>(this IEnumerable<T> enumerable)
        {
            StringBuilder sb = new StringBuilder();
            JoinInternal(enumerable, sb, true);
            return sb.ToString();
        }

        private static bool JoinInternal(IEnumerable enumerable, StringBuilder sb, bool first)
        {
            foreach (var item in enumerable)
            {
                var castItem = item as IEnumerable;
                if (castItem != null)
                {
                    first = JoinInternal(castItem, sb, first);
                }
                else
                {
                    if (!first)
                    {
                        sb.Append(",");
                    }
                    else
                    {
                        first = false;
                    }

                    sb.Append(item);
                }
            }
            return first;
        }
    }