Arrow function

Hi, I have a question, can JSONata have arrow function?

Getting code from this page: https://docs.jsonata.org/programming

```js
$product := function($a, $b) { $a * $b };
$factorial := function($n) { $n = 0 ? 1 : $reduce([1..$n], $product) };
```

The code can be written as follows:

```js
$product := ($a, $b) => $a * $b;
$factorial := $n => $n = 0 ? 1 : $reduce([1..$n], $product);
```

Regards.