Functor (A * (B * C)) ((A * B) * C) := (fst * (fst o snd)) * (snd o snd).
Require Import HoTT.Basics HoTT.Types. Require Import Category.Core Functor.Core InitialTerminalCategory.Core InitialTerminalCategory.Functors Category.Prod Functor.Prod Functor.Composition.Core Functor.Identity Functor.Composition.Laws.