old_contents: import React from 'react';
  import ReactDOM from 'react-dom';
  import './index.css';
  import App from './App';
  import registerServiceWorker from './registerServiceWorker';
  import Navbar from './components/Navbar.js';
  import Header from './components/Header.js';
  import Home from './components/Home.js';
  import Instruction from './components/Instruction.js';
  import AboutUs from './components/AboutUs.js';
  import ContactForm from './components/ContactForm.js';
  import ColorBlindnessView from './components/ColorBlindnessView.js';
  
  import { BrowserRouter as Router, Route, Link } from 'react-router-dom'
  
  const OtherComponent = () => (
   <div>Other component is rendered as well</div>
  )
  
  const root = document.getElementById('root');
  
  ReactDOM.render(
  <Router>
      <div>
        <Navbar></Navbar>
        <hr/>
        <Header></Header>
        <Route exact path="/" component={Home}/>
        {/*<Route exact path="/" component={OtherComponent}/>*/}
  
        <Route path="/instructions" component={Instruction}/>
        <Route path="/quiz" component={App}/>
        <Route path="/about-us" component={AboutUs}/>
        <Route path="/contact-us" component={ContactForm}/>
        <Route path="/color-view" component={ColorBlindnessView}/>
      </div>
    </Router>,
   root);
  registerServiceWorker();
  
new_contents: import React from 'react';
  import ReactDOM from 'react-dom';
  import './index.css';
  import App from './App';
  import registerServiceWorker from './registerServiceWorker';
  import Navbar from './components/Navbar.js';
  import Header from './components/Header.js';
  import Home from './components/Home.js';
  import Instruction from './components/Instruction.js';
  import AboutUs from './components/AboutUs.js';
  import ContactForm from './components/ContactForm.js';
  import ColorBlindnessView from './components/ColorBlindnessView.js';
  import { BrowserRouter as Router, Route, Link } from 'react-router-dom'
  
  const root = document.getElementById('root');
  
  ReactDOM.render(
  <Router>
      <div>
        <Navbar></Navbar>
        <hr/>
        <Header></Header>
        <Route exact path="/" component={Home}/>
        {/*<Route exact path="/" component={OtherComponent}/>*/}
  
        <Route path="/instructions" component={Instruction}/>
        <Route path="/quiz" component={App}/>
        <Route path="/about-us" component={AboutUs}/>
        <Route path="/contact-us" component={ContactForm}/>
        <Route path="/color-view" component={ColorBlindnessView}/>
      </div>
    </Router>,
   root);
  registerServiceWorker();
  
subject: Remove unused lines of code.