title: Return type of a `yield call`
body: <p>I've noticed that the result of a <code>yield call</code> effect is typed as <code>any</code> when used as</p>
  
  <pre><code>const data = yield call(f);
  </code></pre>
  
  <p>while <code>f</code> is a <code>() =&gt; Promise&lt;number&gt;</code> function.</p>
  
  <p>Am I missing something or is it a <code>redux-saga</code> typings limitation?</p>