∀ {M : Type u_1} {N : Type u_2} {X : Type u_3} {Y : Type u_4} {σ : M → N} [inst : SMul M X] [inst_1 : AddGroup Y]
  [inst_2 : DistribSMul N Y] (x x_1 : X →ₑ[σ] Y), x - x_1 = x + { toFun := -⇑x_1, map_smul' := ⋯ }