fact: Definition cyl_extension {A B} (f : A -> B) (C : Cyl f -> Type) (g : forall a, C (cyl a)) (ext : ExtensionAlong cyl C g) : ExtensionAlong cyl C g.
imports: HoTT.Basics HoTT.Types Equiv.PathSplit PathAny Cubical.DPath Cubical.DPathSquare Colimits.Coeq Colimits.MappingCylinder