implementing delegate in interface
<p>I can't find a way to implement delegate in interface</p>

<p>I want to get this:</p>

<pre><code>public class SomeClass : ISomeInterface
{
    public delegate void SomeCallback();
    public SomeCallback callback;

    public void SomeMethod()
    {
         callback.invoke();
    }
}

public class MainClass
{
    void Callback() { Console.WriteLine("Callback"); }

    public void Start()
    {
         SomeClass s = new SomeClass();
         s.callback = Callback;
         s.SomeMethod();
    }
}
</code></pre>

<p>but in case when I create instance of the class "SomeClass" using interface:</p>

<pre><code>public class MainClass
{

    void Callback() { Console.WriteLine("Callback"); }

    public void Start()
    {
         ISomeInterface s = new SomeClass();   // &lt;&lt;&lt;----
         s.callback = Callback;                // here will be an error :(
         s.SomeMethod();
    }
}
</code></pre>

<p>Please, help me with it :)</p>