fact: Definition extendable_postcompose' (n : nat) {A B : Type} (C D : B -> Type) (f : A -> B) (g : forall b, C b <~> D b) : ExtendableAlong n f C -> ExtendableAlong n f D.
imports: HoTT.Basics HoTT.Types Equiv.PathSplit PathAny Cubical.DPath Cubical.DPathSquare Colimits.Coeq Colimits.MappingCylinder