using System;

using System.Dynamic;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        dynamic x = new ExpandoObject();

        AddProperty(x, "Language", "English");

        Console.WriteLine(x.Language);

    }

    public static void AddProperty(ExpandoObject expando, string propertyName, object propertyValue)

{

    // ExpandoObject supports IDictionary so we can extend it like this

    var expandoDict = expando as IDictionary<string, object>;

    if (expandoDict.ContainsKey(propertyName))

        expandoDict[propertyName] = propertyValue;

    else

        expandoDict.Add(propertyName, propertyValue);

}

}