//can't use typeof
>typeof MinKey
object

//not === comparable (should make singleton?)
> db.max.findOne()._id
{ "$maxKey" : 1 }
> db.max.findOne()._id === MaxKey
// no instanceof support...
> "a" instanceof MinKey
Fri Jan 18 18:07:21.863 javascript execution failed (shell):1 TypeError: Expecting a function in instanceof check, but got a
"a" instanceof MinKey