fact: Definition second `(f : a -> b) `(x : z * a) : z * b := match x with (z, b) => (z, f b) end.
imports: Coq.Lists.List Category.Lib Category.Theory.Coq.Functor Category.Theory.Coq.Applicative Category.Theory.Coq.Monad Category.Theory.Coq.Semigroup Category.Theory.Coq.Monoid