∀ {R : Type u_1} {A : Type u_2} {M : Type u_4} [inst : CommSemiring R] [inst_1 : CommSemiring A]
  [inst_2 : AddCommMonoid M] [inst_3 : Algebra R A] [inst_4 : Module A M] [inst_5 : Module R M]
  {D1 D2 : Derivation R A M}, D1 = D2 → ∀ (a : A), D1 a = D2 a