fact: Definition left_triple {A B C} (x : A) (y : B) (z : C) : A * B * C := ((x, y), z).
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