old_contents: import React from 'react';
  import {Route} from 'react-router';
  import App from 'views/App';
  import VideoPage from 'views/VideoPage';
  import TutorialPage from 'views/TutorialPage';
  import NotFound from 'views/NotFound';
  import Redirect from 'views/Redirect';
  
  export default (
    <Route component={App}>
      <Route path=":domainSlug/:subjectSlug/:topicSlug/:tutorialSlug" component={TutorialPage}>
        <Route path="v/:videoReadableId" component={VideoPage}/>
      </Route>
      <Route path="*" component={NotFound}/>
    </Route>
  );
  
new_contents: import React from 'react';
  import {Route} from 'react-router';
  import App from 'views/App';
  import VideoPage from 'views/VideoPage';
  import TutorialPage from 'views/TutorialPage';
  import NotFound from 'views/NotFound';
  import Redirect from 'views/Redirect';
  
  class Dummy {
    render() {
      return <div>
        {this.props.children}
      </div>;
    }
  }
  
  export default (
    <Route component={App}>
      <Route path=":domainSlug" component={Dummy}>
        <Route path=":subjectSlug" component={Dummy}>
          <Route path=":topicSlug" component={Dummy}>
            <Route path=":tutorialSlug" component={TutorialPage}>
              <Route path="v/:videoReadableId" component={VideoPage}/>
            </Route>
          </Route>
        </Route>
      </Route>
      <Route path="*" component={NotFound}/>
    </Route>
  );
  
subject: Expand route hierarchy