title: Proper way to dispose a one-off observable in RxSwift
body: <p>I have an observable that I only want to kick off once. The docs say:</p>
  
  <blockquote>
    <p>Using dispose bags or takeUntil operator is a robust way of making sure resources are cleaned up. We recommend using them in production even if the sequences will terminate in finite time.</p>
  </blockquote>
  
  <p>My observable terminates after just one event</p>
  
  <pre><code>let observable = Observable.create() { observer in
    webservice.makeHTTPRequestWithCompletionBlock {
      if something {
        observer.on(.Next(...))
        observer.onCompleted()
      } else {
        observer.on(.Error(...))
      }
    }
  }
  </code></pre>
  
  <p>Say I wasn't interested in cancelling subscribers to this observable, I just want it run once and complete. I want the lifecycle of this observable to end when the work itself is completed. Meaning there are no good candidates for disposeBag that I can see. takeUntil also expects an 'event', and there are no good ones that I can see. </p>
  
  <p>Right now I just solve the warning by throwing away the disposable:</p>
  
  <pre><code>_ = observeable.subscribeNext { ... }
  </code></pre>
  
  <p>Is there a way to do this, or a different paradigm that I should use?</p>