text: import React, { Component } from "react";
  import { Link } from "react-router-dom";
  
  class Header extends Component {
      render() {
          return (
              <div className="App-header">
                  <p>
                      <Link to="/">Home</Link> | 
                      <Link to="/login">Login</Link> | 
                      <Link to="/about">About</Link> | 
                      <Link to="/topics">Topics</Link> |
                  </p>
              </div>
          );
      }
  }
  export default Header;