Heat equation example from documentation

Dear all,

I was looking at the heat equation example from the documentation (the first one at https://doc.freefem.org/models/evolution-problems.html) and I have a doubt. Shouldn’t f be defined as a func and not as an element of fespace in the code? The two writings should not be equivalent, and from the variational formulation I would have expected an analytic function, not an element of the FE space. Am I missing something?

Best regards,