Yes. Lambdas in Python are awkward, but you can definitely use either a lambda or a named function.

In fact, you could define a number of useful precondition functions in a single module and use them throughout a project. A couple of higher-order functions could make the post's examples safer and nicer-looking too. For example:

    @precondition(starts_with('The year is '))

where the starts_with precondition is:

    def starts_with(param):
        def test(s):
            return s.startswith(param)
        return test