{A B : Type} (C D : B -> Type) (f : A -> B) (g : forall b, C b -> D b) `{forall b, IsEquiv (g b)} : ooExtendableAlong f C -> ooExtendableAlong f D := fun ppp n => extendable_postcompose n C D f g (ppp n).
Require Import HoTT.Basics HoTT.Types. Require Import Equiv.PathSplit Homotopy.IdentitySystems. Require Import Cubical.DPath Cubical.DPathSquare. Require Import Colimits.Coeq Colimits.MappingCylinder.