{X X' : SSet.Truncated 2} →
  (Y : SSet.Truncated 2) →
    (f : X ⟶ X') →
      ((SSet.Truncated.mapHomotopyCategory f).prod (CategoryTheory.Functor.id Y.HomotopyCategory)).comp
          (SSet.Truncated.HomotopyCategory.BinaryProduct.inverse X' Y) ≅
        (SSet.Truncated.HomotopyCategory.BinaryProduct.inverse X Y).comp
          (SSet.Truncated.mapHomotopyCategory (CategoryTheory.MonoidalCategoryStruct.whiskerRight f Y))