title: Should I use both `import 'rxjs/Rx'` and `import { Observable } from '@rxjs/Observable'`
body: <pre><code>import { Injectable } from '@angular/core';
  import { Headers, Http, Response } from '@angular/http';
  import { Observable } from '@rxjs/Observable';
  import 'rxjs/Rx';
  import 'rxjs/add/observable/throw';
  @Component({});
  export shellModule{}
  </code></pre>
  
  <p>This is a piece of code form my Angular app that I copied from somewhere (I have removed the definitions in the exported module. I am using it to make a service to call APIs.</p>
  
  <p>In the imports in this particular file, why is it that Observable is imported separately even though the entire <strong>rxjs</strong>has been imported. If a particular module is being imported in its entirety, why is a particular object from it imported separately? I tried asking this question at the forum from where I took it, but there was no answer. I want to understand if this somehow helps with optimization of code.</p>