title: How to hide header of createStackNavigator on React Native?
body: <p>I want to hide header because I already have styled Toolbar in code:</p>
  
  <pre><code>import {createStackNavigator}
  from 'react-navigation'
  const AppStackNavigator = createStackNavigator ({
    Home: HomePage,
    Friend: AddFriend,
    Bill: AddBill,
  })
  class App extends Component {
  render() {
    return (
    &lt;AppStackNavigator initialRouteName='Home'/&gt;`&lt;br&gt;
    );
    }
  }
  export default App;
  </code></pre>
  
  <p>What should I add to my code?</p>