# Custom awaitable and awaiter types in C# 5.0 asynchronous

In C# 5.0 you can use the `await` keyword to await an `awaitable` object. But what is the minimum requirement for an object to be considered `awaitable` by C#? Interestingly there are no interfaces to be implemented in order to be considered `awaitable`!  
Having a parameter-less method named `GetAwaiter()` which returns an `awaiter` object is the only convention for a type to be recognized `awaitable` by C#:

// This class is awaitable because it has the GetAwaiter method, provided MyAwaiter is an awaiter.
public class MyWaitable
{
    public MyAwaiter GetAwaiter()
    {
        return new MyAwaiter();
    }
}

Now the question is how to make a type `awaiter`? The minimum requirements for a type to be `awiater` are implementing the `INotifyCompletion` interface, and having the `IsCompleted` property and the `GetResult` method with the following signatures:

public class MyAwaiter : INotifyCompletion
{
    public void OnCompleted(Action continuation)
    {
        
    }

    public bool IsCompleted
    {
        get
        {
            return false;
        }
    }


    public void GetResult()
    {
       
    }
}