I think it's still pretty unclear what this function might do, since the inverse of a map isn't well-defined. I think this is a type signature that makes sense

I think it's still pretty unclear what this function might do, since the inverse of a map isn't well-defined. I think this is a type signature that makes sense and has a fairly obvious most-likely meaning: boo :: Map a b -> b -> Set a I'm not sure how you would conjure up just an 'a' in general.