I am learning `react native`. I am trying to understand the code [Here](https://github.com/facebook/react-native/blob/master/RNTester/js/PanResponderExample.js). The snippet below seems very weird to me. Can you please explain what it does?

```
circle: (null : ?{ setNativeProps(props: Object): void })

```

I know about `if` statement like:

```
blabla = (if-this-is-true) ? this-should-be-used : otherwise_this

```

but don't know if the circle one is the same thing.