Requisite that streams one throwable and one non-throwable?

[Barry Wark]

I would like to check a fact such as 

(fact "`my-fn` handles throw exceptions on first call to `might-throw`"

  (my-fn "foo") => "bar"

  (provided

    (might-throw "foo") =streams=> [(Exception.) "bar"])))

I know that I could use

(fact "`my-fn` handles throw exceptions on first call to `might-throw`"

  (my-fn "foo") => "bar"

  (provided

    (might-throw "foo") =throws=> (Exception.)))

for the first throwable, and =streams=> for multiple return values, but can't find a way to combine these. 

When there isn't a good way in Midje, I suspect I'm on the wrong path. What's a better way to proceed?

Thanks,

Barry