title: File 'app/hero.ts' is not a module error in the console, where to store interfaces files in directory structure with angular2?
body: <p>I am doing the <code>angular2</code> tutorial at this address: <a href="https://angular.io/docs/ts/latest/tutorial/toh-pt3.html" rel="noreferrer">https://angular.io/docs/ts/latest/tutorial/toh-pt3.html</a> I have put the <code>hero</code> interface in a single file under the <code>app</code> folder, in the console I have this error:</p>
  
  <pre><code>app/app.component.ts(2,20): error TS2306: File 'app/hero.ts' is not a module.
  [0] app/hero-detail.component.ts(2,20): error TS2306: File 'app/hero.ts' is not a module.
  </code></pre>
  
  <p>If I put my interface file in a hero folder the error disappear, <strong>this is not mentioned in the documentation, what's wrong with my import</strong>?</p>
  
  <p>My import directive (at the beguining of the component files) in both <code>app.components.ts</code> and <code>hero-detail.component.ts</code>:</p>
  
  <pre><code>import {Component} from 'angular2/core';
  
  import {Hero} from './hero';
  </code></pre>
  
  <p><strong>Must I replace</strong> my import directive by: <code>import {Hero} from './';</code> <strong>or simply put the code in a hero folder</strong>?</p>