∀ {R : Type u_2} {A : Type u_1} [inst : CommSemiring R] [inst_1 : Ring A] [inst_2 : Algebra R A] {r : Rˣ} {s : R}
  {a : A} (h : IsUnit (r • (algebraMap R A) s - a)), r • ↑h.unit⁻¹ * ((algebraMap R A) s - r⁻¹ • a) = 1