[racket-dev] typed/scheme n00b question

I'd like to write a typed/racket or typed/racket/base program that uses "file-or-directory-modify-seconds". I get this error:

Type Checker: untyped identifier file-or-directory-modify-seconds imported from module <typed/racket/base> in: file-or-directory-modify-seconds

If this function were acquired using a 'require', I see that I could use 'require/typed' to associate a type with it.  I don't see how to apply this to functions that come in as part of the language.

I tried various decorations to wrap the use of the function in checks, but then realized that the type checker wasn't complaining that the value had the 'Any' type, but instead that the value was untyped, which suggests that type-futzing (checking that it's a procedure, etc.) was unlikely to help.

What's the (presumably obvious?) solution to this?

John

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