Definition double_transport {C : precategory_ob_mor} {a a' b b' : ob C} (p : a = a') (q : b = b') (f : a --> b) : a' --> b' := transportf (λ c, a' --> c) q (transportf (λ c, c --> b) p f).
Require Import UniMath.Foundations.PartA. Require Import UniMath.Foundations.Sets. Require Import UniMath.MoreFoundations.PartA. Require Import UniMath.MoreFoundations.Tactics. Require Import UniMath.CategoryTheory.Core.Categories. Require Import UniMath.CategoryTheory.Core.Isos.