fact: Definition extendable_homotopy (n : nat) {A B : Type} (C : B -> Type) (f : A -> B) (h k : forall b, C b) : ExtendableAlong n.+1 f C -> ExtendableAlong n f (fun b => h b = k b).
imports: HoTT.Basics HoTT.Types Equiv.PathSplit PathAny Cubical.DPath Cubical.DPathSquare Colimits.Coeq Colimits.MappingCylinder