text: import React from 'react';
  import {
  Route,
  NavLink,
  HashRouter
  } from 'react-router-dom';
  import '../App.css';
  import logo from '../logo.svg';
  import App from '../App';
  import Edit from './Edit';
  import Create from './Create';
  import Show from './Show';
  import Register from './Register';
  import Login from './Login';
  // import { connect } from 'react-redux';
  import Logout from './Logout';
  import Uploader from './Uploader';
  import Resume from './Resume';
  
  class Navigation extends React.Component {
    constructor(props) {
      super(props);
      this.loggedIn = sessionStorage.getItem('user'); 
    }
    render() {
      let userMessage;
      if (!this.loggedIn) {
        userMessage = (
          <ul className="nav navbar-nav">
            <li className="nav-item">
             <NavLink to="/login">Login</NavLink>
            </li>
            <li className="nav-item">
             <NavLink to="/register">Registration</NavLink>
            </li>
            <li className="nav-item">
             <NavLink to="/uploader">Upload</NavLink>
            </li>
          </ul>
        )
      } else {
        userMessage = (
           <ul className="nav navbar-nav">
            <li className="nav-item">
              <NavLink to="/">Home</NavLink>
            </li>
            <li className="nav-item">
              <NavLink to="/create">Add Book</NavLink>
            </li>
            <li className="nav-item">
             <NavLink to="/resume">Resume</NavLink>
            </li>
            <li className="nav-item">
             <NavLink to="/logout">Logout</NavLink>
            </li>
          </ul> 
        )
      }
      return (
        <HashRouter>
          <div>
          <nav className="navbar navbar-expand-md bg-dark navbar-dark">
        <a className="navbar-brand" href="#"><img src={logo} className="App-logo" alt="logo" height="20px"/></a>
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#collapsibleNavbar" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
          <span class="navbar-toggler-icon"></span>
        </button>
        <div className="collapse navbar-collapse" id="collapsibleNavbar">
            { userMessage }
        </div>  
      </nav>
            <div className="content">
              <Route exact path="/" component={App}/>
              <Route path="/create" component={Create} />
              <Route path="/login" component={Login} />
              <Route path="/logout" component={Logout} />
              <Route path="/uploader" component={Uploader} />
              <Route path="/register" component={Register} />
              <Route path='/edit/:id' component={Edit} />
              <Route path='/show/:id' component={Show} />
              <Route path='/resume' component={Resume} />
            </div>
          </div>
      </HashRouter>
      )
    }
  }
  
  export default Navigation;
  