const Nav = ({ activeTab, onTabChange }) => (
    <nav className="App-nav" >
      <ul>
        <li className={`App-nav-item ${activeTab === 0 && 'selected'}`} >
          <a onClick={() => onTabChange(0)} > Items </a>
        </li>
        <li className={`App-nav-item ${activeTab === 1 && 'selected'}`} >
          <a onClick={() => onTabChange(1)} > Cart </a>
        </li>
     </ul>
    </nav>
);