∀ {𝕜 : Type u_1} {E : Type u_2} [inst : NormedAddCommGroup E] [inst_1 : NontriviallyNormedField 𝕜]
  [inst_2 : NormedSpace 𝕜 E] (n : ℕ) (a : E →L[𝕜] E),
  SubNegMonoid.zsmul (Int.negSucc n) a = -SubNegMonoid.zsmul (↑n.succ) a