title: Create an IObservable sequence from an unidentified number of sequences
body: <p>i have an observable sequence like :-</p>
  
  <pre><code>Observable.FromEventPattern&lt;PropertyChangedEventArgs&gt;(&lt;source&gt;, "PropertyChanged").Subscribe(changed =&gt;
                  {
  
  }
  </code></pre>
  
  <p>Now my one property for which the above code fires also change 3-5 more properties, for each of which again the above code fires up.</p>
  
  <p>Now i want to get to the last point of this sequence which i dont know how many times it will fire up.</p>
  
  <p>i tried to create another IObservable sequnce from the above code, but dont know when will the new sequence that i create will be used. I tried :-</p>
  
  <pre><code> Observable.FromEventPattern&lt;PropertyChangedEventArgs&gt;(&lt;source&gt;, "PropertyChanged").Subscribe(changed =&gt;
                  {
                      if (testObs == null)
                      {
                          testObs = a(changed.EventArgs.PropertyName).ToObservable();
                      }
                      else
                      {
                          testObs.Concat(a(changed.EventArgs.PropertyName).ToObservable());
                      }
  }
  </code></pre>
  
  <p>On the whole i want to get to the end point of the sequence, that i am creating everytime that code on top fires up.</p>
  
  <p>Any idea guys, Please help..!!</p>