∀ {X Y : SSet.Truncated 2}
  (x : X.obj (Opposite.op { obj := SimplexCategory.mk 0, property := SSet.Truncated.Edge.tensor._proof_1 }))
  (y : Y.obj (Opposite.op { obj := SimplexCategory.mk 0, property := SSet.Truncated.Edge.tensor._proof_1 })),
  (SSet.Truncated.HomotopyCategory.BinaryProduct.functorCompInverseIso X Y).hom.app
      (SSet.Truncated.HomotopyCategory.mk (x, y)) =
    CategoryTheory.CategoryStruct.id
      (((SSet.Truncated.HomotopyCategory.BinaryProduct.functor X Y).comp
            (SSet.Truncated.HomotopyCategory.BinaryProduct.inverse X Y)).obj
        (SSet.Truncated.HomotopyCategory.mk (x, y)))