Calling a function like this “ensureUser” is pretty idiomatic and useful, in lisp-style code bases. I think it’s a pattern related to “parse, don’t validate” in static-type lands: rather than _checking_ what the type is and throwing an error, you define a function that knows how to turn various representations of your type into its canonical shape.

Right so we have:

    function find_user(person: string)

and also:

    function find_user(person: Object)

how long before someone writes this:

    find_user(person: { name: "dave" })

meanwhile, someone else, not suspecting that they'll be handed a weird half-formed `User` object adds `person.id` somewhere in the body of the Object version of `find_user` and now we have a weird edge-case where very rarely `find_user` panics because the user object we're handed doesn't have an id??? Great, I just lost an hour trying to dig that out of the logs, and the users are starting to think of the product as flakey because the bug has been in prod for over a month before we finally believed them enough to look into it.

Just. Use. Types. Multiple dispatch won't save you on its own. You NEED compile-time types.