title: Why there's no `Single#doOnTerminate` method in RxJava?
body: <p>RxJava's <a href="http://reactivex.io/RxJava/javadoc/rx/Observable.html#doOnTerminate(rx.functions.Action0)" rel="nofollow noreferrer">Observable</a> has both <code>doOnTerminate</code> and <code>doAfterTerminate</code> methods.</p>
  
  <p>The difference is that <code>doOnTerminate</code> is called <em>before</em> <code>onCompleted</code> or <code>onError</code> whereas <code>doAfterTerminate</code> is called <em>after</em>. Both methods seem useful.</p>
  
  <p><a href="http://reactivex.io/RxJava/javadoc/rx/Single.html#doAfterTerminate(rx.functions.Action0)" rel="nofollow noreferrer">Single</a> however, has only <code>doAfterTerminate</code>. </p>
  
  <p>Is there a reason why <code>Single</code> does not have <code>doOnTerminate</code> method?</p>