old_contents: /*
  	High level presentation component for entire front-end applicaiton
  	index > app > nav & view
  */
  import React from 'react'
  import Main from './main/main'
  
  // a "location" state variable and then selectively display a Component based on the value
  var location = 'MAIN_PAGE'
  
  // TODO :  routing logic to determine which view to display.
  export const App = () => (
      <div>
          <div>Hello React!</div>
          <div>
              <Main />
          </div>
  
      </div>
  
      // if (location == 'MAIN_PAGE') {
      //     <Main />
      // } else if (location == 'PROFILE_PAGE') {
      //     <Profile />
      // } else {
      //     <Landing />
      // }
  )
  
  
  // TODO : Additionally we might have compound views, including a navigation section
  
  export default App
new_contents: /*
  	High level presentation component for entire front-end applicaiton
  	index > app > nav & view
  */
  import React from 'react'
  import Main from './main/main'
  import Profile from './profile/profile'
  import Landing from './auth/landing'
  
  // TODO :  routing logic to determine which view to display.
  class App extends React.Component {
  
      constructor(props) {
          super(props)
          this.state = {
              // a route state variable and then selectively
              // display a Component based on the value
              route : window.location.hash.substr(1)
          }
      }
  
      componentDidMount() {
          window.addEventListener('hashchange', () => {
              this.setState({
                  route: window.location.hash.substr(1)
              })
              console.log(this.state.route)
          })
      }
  
      render() {
          let Child
          switch (this.state.route) {
              case '/main': Child = Main; break;
              case '/profile': Child = Profile; break;
              default: Child = Landing;
          }
          return (
              <div>
                  <h1>App</h1>
                  <ul>
                      <li><a href="#/">Landing</a></li>
                      <li><a href="#/main">Main</a></li>
                      <li><a href="#/profile">Profile</a></li>
                  </ul>
                  <Child/>
              </div>
          )
      }
  }
  
  
  
  // TODO : Additionally we might have compound views, including a navigation section
  
  export default App
subject: Add routing logic for three views.