什么是Util.KeepRunning（）？

Question

我阅读了以下代码。代码中的Util.KeepRunning()是什么？似乎是在等待异步方法完成。但是为什么它需要一次性使用？

var observable = Observable.Create<char>(async (observer, cancel) =>
{
    for (var i = 0; !cancel.IsCancellationRequested && i < 100; i++)
    {
        observer.OnNext(await GetCharAsync());
    }
});

//Here's how you can use it in LINQPad, for example:

// Create a disposable that keeps the query running.
// This is necessary, since the observable is 100% async.
var end = Util.KeepRunning();

observable.Subscribe(
    c => Console.WriteLine(c.ToString()),
    () => end.Dispose());