Support () =< {} arrow functions

I've never understood why the arrows in arrow function signatures have to go left-to-right. It's 2021 – that arrow should be able to go in any direction it wants to go in life!

Expected syntax:
```javascript
let func = () => { console.log('the functino has run'); };
```
Proposed syntax:
```javascript
let func = () =< { console.log('the functino has run'); };
```