* {(state) => (
*
* I'm A fade Transition!
*
* )}
*
* );
* ```
*
* As noted the `Transition` component doesn't _do_ anything by itself to its child component.
* What it does do is track transition states over time so you can update the
* component (such as by adding styles or classes) when it changes states.
*
* There are 4 main states a Transition can be in:
* - `ENTERING`
* - `ENTERED`
* - `EXITING`
* - `EXITED`
*
* Transition state is toggled via the `in` prop. When `true` the component begins the
* "Enter" stage. During this stage, the component will shift from its current transition state,
* to `'entering'` for the duration of the transition and then to the `'entered'` stage once
* it's complete. Let's take the following example:
*
* ```jsx
* state= { in: false };
*
* toggleEnterState = () => {
* this.setState({ in: true });
* }
*
* render() {
* return (
*