title: Multiple subscriptions to Observable
body: <p>I create my own <code>Observable</code> and subscribed two functions to it. I would expect to have both functions executed for each element in the sequence but only the last one is. </p>
  
  <pre class="lang-js prettyprint-override"><code>let observer = null
  const notificationArrayStream = Rx.Observable.create(function (obs) {
    observer = obs;
    return () =&gt; {}
  })
  
  function trigger(something) {
    observer.next(something)
  }
  
  notificationArrayStream.subscribe((x) =&gt; console.log('a: ' + x))
  notificationArrayStream.subscribe((x) =&gt; console.log('b: ' + x))
  
  trigger('TEST')
  </code></pre>
  
  <p>Expected output</p>
  
  <pre><code>a: TEST
  b: TEST
  </code></pre>
  
  <p>Actual output</p>
  
  <pre><code>b: TEST
  </code></pre>
  
  <p>Here's the JSBin: <a href="http://jsbin.com/cahoyey/edit?js,console" rel="noreferrer">http://jsbin.com/cahoyey/edit?js,console</a></p>
  
  <p>Why is that? How can I have multiple functions subscribed to a single <code>Observable</code>?</p>