title: Knockout.js custom function returning function instead of value
body: <p>This seems like a straightforward implementation:</p>
  
  <pre><code>ko.observableArray.fn.findEl = function(id) {
      return ko.computed(function() {
        var ary = this();
        return _.any(ary, function(user) { return user.id() === id;});
      }, this);
  };
  </code></pre>
  
  <p>But when I call it like:</p>
  
  <pre><code>user.current.following.findEl(valueAccessor())
  </code></pre>
  
  <p>It returns a function, requiring me to call findEl like:</p>
  
  <pre><code>user.current.following.findEl(valueAccessor())()
  </code></pre>
  
  <p>which is needless to say, not ideal.  </p>