text: import React from "react";
  import {BrowserRouter as Router,Switch,Route,Link} from "react-router-dom";
  import Home from "./pages/Home.js";
  import About from "./pages/About.js";
  import Category from "./category/Index.js";
  import List from "./category/List.js";
  import Add from "./category/Add.js";
  import Edit from "./category/Edit.js";
  import Error404 from "./pages/Error404.js";
  
  
  function Header(){
  
  	return(
  				 <div>
  				 <nav className="navbar navbar-expand-lg navbar-light bg-secondary">
  				  <a className="navbar-brand" href="#">Navbar</a>
  
  				  <div className="collapse navbar-collapse" id="navbarSupportedContent">
  				    <ul className="navbar-nav mr-auto">
  				      <li className="nav-item">
  				        <Link className="nav-link" to="/">Home</Link>
  				      </li>
  				      <li className="nav-item">
  				        <Link className="nav-link" to="/about">About</Link>
  				      </li>
  				      <li className="nav-item">
  				        <Link className="nav-link" to="/categories">Categories</Link>
  				      </li>
  				    </ul>
  				    <form className="form-inline my-2 my-lg-0">
  				      <input className="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search"/>
  				      <button className="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
  				    </form>
  				  </div>
  				</nav>
  
  
  		         <Switch>
  			          <Route exact path="/">
  			            <Home />
  			          </Route>
  			          <Route path="/about">
  			            <About />
  			          </Route>
  			          <Route exact path="/categories">
  			            <Category />
  			          </Route>
  			         <Route exact path="/category">
  			         	<Category />
  			         </Route>
  			         <Route exact path="/category/add">
  			         	<Category />
  			         </Route>
  			         <Route exact path="/category/edit/:id">
  			         	<Category />
  			         </Route>
  			         <Route exact path="/*">
  			         	<Error404 />
  			         </Route>
  		        </Switch>
  		        </div>
  		);
  }
  
  export default Header;