Question: I'm working with Atom, and looking for a Jade/Pug compiler for Atom. 
What's is the best resource at the moment? 

Do I need to add a plugin, or install this in NodeJS?

I need a Pug version and a copy of the compiled source.

Answer: 
To be able to pass `null` in, your type hint has to allow it. In Hack, this is done by using a [nullable type](https://docs.hhvm.com/hack/types/type-system#nullable).

```
private static function myfun(
    string $param1,
    ?:xhp $param2,
): :xhp {
    return
      //somethinf
}

```

The Hack type checker will then also make sure that you check `$param2` is not null before using it.
Does this the trick?
`private static function myfun(
 string $param1,
 :xhp $param2=null,
 ): :xhp {
 return
 //somethinf
 }`