fact: Definition extendable_functor_sigma_id n {A} {P Q : A -> Type} (f : forall a, P a -> Q a) (C : sig Q -> Type) (ef : forall a, ExtendableAlong n (f a) (fun v => C (a;v))) : ExtendableAlong n (functor_sigma idmap f) C.
imports: HoTT.Basics HoTT.Types Equiv.PathSplit PathAny Cubical.DPath Cubical.DPathSquare Colimits.Coeq Colimits.MappingCylinder