title: Getting a promise's value via yield & co
body: <p>I'm trying to figure out how to get the value of a promise via <code>yield</code>, possibly with &quot;co&quot;:</p>
  <pre><code>function *(){
      var someVar = yield functionThatReturnsAPromise();
  }
  </code></pre>
  <p>The called function is not a generator, just a normal function.  With the above, <code>someVar == Promise</code>, but I want the resolved value.  Does <a href="https://github.com/visionmedia/co" rel="nofollow noreferrer">co</a> or some other library have a way of doing this?</p>