Write a function, `every-second-element`, that returns every second element of a list. As examples

(every-second-element '(a b c)) => (a c)

(every-second-element '(a b c d)) => (a c)

It is often worthwhile to go for a *more general solution* than actually needed.
Therefore, program `(every-nth-element n lst)` where `n >= 1` and `lst` is a proper list.

Can you define `every-second-element` in terms of `every-nth-element`?