using System;

​

public delegate void OutputStreamWriter<T>(OutputStream ostr, in T v);

public class  OutputStream

{

    public void WriteString(in string s)

    {

        Console.WriteLine(s);

    }

    public void WriteSeq<T>(OutputStreamWriter<T> writer, T[] seq)

    {

        foreach(T value in seq)

        {

            writer(this, value);

        }

    }

}

​

public class Program

{

    int Main(string[] args)

    {

        var ostr = new OutputStream();

        var values = new string[] {"one", "two", "three" };

        ostr.WriteSeq((ostr, value) => ostr.WriteString(value), values);

        return 0;

    }

}