∀ {X : TopCat} {ι : Type u_1} [inst : CategoryTheory.Category.{v_1, u_1} ι]
  (B : CategoryTheory.Functor ι (TopologicalSpace.Opens ↑X)),
  B.IsCoverDense (Opens.grothendieckTopology ↑X) ↔ TopologicalSpace.Opens.IsBasis (Set.range B.obj)