title: Observable.throw replacement in rxjs 5.5.2
body: <p>I'm migrating to <code>rxjs@5.5.2</code> and using lettable operators... I also update <code>Observable</code> static methods. I wonder what is the counterpart of <code>Observable.throw</code> and <code>import 'rxjs/add/observable/throw';</code>.</p>
  
  <p>Should I import ugly <code>_throw</code>?</p>
  
  <p><code>import { _throw } from 'rxjs/observable/throw';</code></p>
  
  <p>Or there's a better way. Honestly I liked static methods on <code>Observable</code>, and now it seems that all static creating methods like <code>of</code>, <code>from</code> should be imported from <code>rxjs/observable/&lt;methodName&gt;</code> ?</p>