For example, the following code will start a single screen app with two
screens pushed into the stack.

```js
Navigation.startSingleScreenApp({
    components: [
    {
      screen: 'example.Types',
      title: 'Navigation Types',
      overrideBackPress: true
    },
    {
      screen: 'example.Types.CustomButtonScreen',
      title: 'Custom Buttons'
    }
  ]
});
```