∀ {R : Type u_1} {A : Type u_2} [inst : CommRing R] [inst_1 : NonUnitalCommRing A] [inst_2 : Module R A]
  [inst_3 : IsScalarTower R A A] [inst_4 : SMulCommClass R A A] (a b c : Unitization R A), a * b * c = a * (b * c)