Sort u_1 →
  {C : Type u} →
    [inst : CategoryTheory.Category.{v, u} C] →
      {J : CategoryTheory.GrothendieckTopology C} →
        [inst_1 : CategoryTheory.HasWeakSheafify J (Type v)] →
          J.MayerVietorisSquare →
            {C' : Type u} →
              [inst' : CategoryTheory.Category.{v, u} C'] →
                {J' : CategoryTheory.GrothendieckTopology C'} →
                  [inst'_1 : CategoryTheory.HasWeakSheafify J' (Type v)] → J'.MayerVietorisSquare → Sort u_1