一下是一个接口中实现事件的代码，看不懂，还请高手解释下.先谢谢了。
public delegate void TestDelegate();   // delegate declaration

public interface ITestInterface
{
    event TestDelegate TestEvent;
    void FireAway();
}

public class TestClass : ITestInterface
{
    public event TestDelegate TestEvent;

    public void FireAway()
    {
        if (TestEvent != null)
        {
            TestEvent();
        }
    }
}

public class MainClass
{
    static private void F()
    {
        System.Console.WriteLine("This is called when the event fires.");
    }

    static void Main()
    {
        ITestInterface i = new TestClass();

        i.TestEvent += new TestDelegate(F);
        i.FireAway();
    }
}

i.TestEvent += new TestDelegate(F);这个怎么理解呢？