using System;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        var input = new Tuple<int, int>[] {

            Tuple.Create(10, 300),

            Tuple.Create(20, 180),

            Tuple.Create(10, 120),

            Tuple.Create(30, 600)

        };

        var start = DateTimeOffset.Parse("2016-09-30T00:00:00Z");

​

        Console.WriteLine("Expected");

        input.Zip(

                //prepend the original start because it is not included in .scan

                new[] {start}.Concat( 

                    //Keep adding the second value from the tuple onto the accumulator

                    input.Scan(start, (acc, source) => acc.AddSeconds(source.Item2))), 

                (l, r) => Tuple.Create(l, r))

            .ForEach(x => Console.WriteLine(x));

        Console.WriteLine("Actual");

        input.Publish(

            pub => pub.Zip(

                        //prepend the original start because it is not included in .scan

                        new[] {start}.Concat(

                            //Keep adding the second value from the tuple onto the accumulator

                            pub.Scan(start, (acc, source) => acc.AddSeconds(source.Item2))), 

                        (l, r) => Tuple.Create(l, r)))

                       .ForEach(x => Console.WriteLine(x));

    }

}