title: Subscribe to the same event for multiple observables in knockout
body: <p>I was trying to implement the following behavior with knockout: when a user submit his login and password and it is wrong - show him the error message. When the user changes any of the inputs - hide the message.</p>
  
  <p>I tried it with computed observable and understood that this is not the right approach, and after reading documentation I found about <a href="http://knockoutjs.com/documentation/observables.html" rel="nofollow noreferrer">subscribing</a>. So everything works nicely when I subscribe each <code>input</code>. The problem is that I am subscribing both observables to the same event (thus duplicating the code). I know that I can put duplicating code into a function and subscribe each observable to the function, but this also doesn't look so nice to me.</p>
  
  <p>Enough this empty talk, here is my <a href="http://jsfiddle.net/SalvadorDali/c78Ws/" rel="nofollow noreferrer">fiddle</a> (click on make it wrong and then type something in <code>input</code>)and here is how I am doing this:</p>
  
  <pre><code>this.loginText.subscribe(function () {
     self.isError(false);
  });
  
  this.passwordText.subscribe(function () {
     self.isError(false);
  });
  </code></pre>
  
  <p>I tried to read <a href="https://stackoverflow.com/q/9278497/1090562">similar question here</a>, but was not able to understand how exactly I can subscribe multiple observables to the same event.</p>