Mixin declarations as AtRule

[ubermanu]

Hey I have a question regarding mixins

Is there a reason why their definition is not recognized as an AtRule?

For example I would expect:

.foo(@color: blue) {
  color: @color;
}

to return an AtRule (not a rule) with the corresponding params

I saw in the mixin test against this case (commented) that it was supposed to bo a valid CSS selector but I'm pretty sure:

.foo(something) { }

is not valid anyway, since the open paren is not preceded by a decorator

I also found some old discussions mentioning some parser options for that stuff, but couldn't find any trace of it in the current codebase

What is your take on this?

I'll post a PR that adress this issue (if it ever is)