title: RxJS - split Observable into two, wait for first to finish
body: <p>I have an Observable that looks more or less like this:</p>
  
  <pre><code>-a--b-c---d--e----f---&gt;
  </code></pre>
  
  <p>where a, b, c, d, e, f are emitted values.</p>
  
  <p>I want to split this Observable into two Observables, in such way that the last emitted value is "alone".</p>
  
  <pre><code>-a--b-c---d--e--------&gt;
  
  ------------------f---&gt;
  </code></pre>
  
  <p>Now, I want to wait for first Observable to completely finish (even inner Observables), after that, execute second Observable.</p>
  
  <p>I know, that I should probably use concat, but I'm actually struggling with splitting Observable into two</p>