{A B : Type} (C : B -> Type) (f : A -> B) {g : A -> B} (p : f == g) : ooExtendableAlong f C -> ooExtendableAlong g C := fun extf n => extendable_homotopic n C f p (extf 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.