∀ {R : Type u_2} {A : Type u_3} {B : Type u_1} [inst : CommSemiring R] [inst_1 : AddCommMonoid A] [inst_2 : Module R A]
  [inst_3 : Coalgebra R A] [inst_4 : AddCommMonoid B] [inst_5 : Module R B] [inst_6 : CoalgebraStruct R B]
  (f : A ≃ₗc[R] B),
  ↑(TensorProduct.assoc R B B B) ∘ₗ LinearMap.rTensor B CoalgebraStruct.comul ∘ₗ CoalgebraStruct.comul =
    LinearMap.lTensor B CoalgebraStruct.comul ∘ₗ CoalgebraStruct.comul