title: Pass a variable to a observable
body: <p>I'm currently using an observable in the following way:</p>
  
  <pre><code>this._socket.onMessage.subscribe(
      (message) =&gt; {
  
      }
  );
  </code></pre>
  
  <p>which works fine! However, Would it be possible to pass a variable to the observable that would allow for some logic?</p>
  
  <p>For example by passing a variable "name" to onMessage, I could subscribe only to events whos name is something specific? Like this:</p>
  
  <pre><code>this._socket.onMessage(name-variable).subscribe(
      (message) =&gt; {
          // only get events that is related to the name-variable
      }
  );
  </code></pre>