title: How to manually send next signal to a observable in RxSwift?
body: <p>I create an observable using the following code:</p>
  
  <pre><code>let disposeBag = DisposeBag()
  
  let myJust = { (element: String) -&gt; Observable&lt;String&gt; in
      return Observable.create { observer in
          observer.on(.next(element))
          //observer.on(.completed)
          return Disposables.create()
      }
  }
  </code></pre>
  
  <p>That code comes from RxSwift's sample code. </p>
  
  <p>If I create an empty Observable <code>myJust</code>, and later I try to send it a value:</p>
  
  <pre><code>myJust("").on(.completed)
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>error: value of type 'Observable&lt;String&gt;' has no member 'on'
  </code></pre>