[mediaqueries] Use custom media queries in custom media query definitions?

The spec didn't say if this is possible:

@custom-media --foo (width < 10em);
@custom-media --bar (--foo);

And what happens when there are circular references:

@custom-media --foo (--foo);
@custom-media --bar (--baz);
@custom-media --baz (--bar);

I hope reusing custom media queries is possible, and circular references evaluate to false.