title: Reactive UI how to use WhenAny using two properties?
body: <p>I am trying to use WhenAny (Reactive UI) for the first time.</p>
  
  <p>When a Identifier =="xyz" and a IsMax field get changes, want to set a local value to true in the subscribe, </p>
  
  <pre><code>   this.WhenAny(x =&gt; x.IsMax, x =&gt; x.Value)
         .Subscribe(x =&gt; 
              {
                  if (Identifier == "xyz")
                  {  
                     isOk = true; 
                  }
              });
  </code></pre>
  
  <p>but is there any other way to merge Identifier condition as well?</p>