∀ (R : Type u) (S : Type v) [inst : CommRing R] [inst_1 : CommRing S] [inst_2 : Algebra R S] (x y z : S),
  ((KaehlerDifferential.kerTotal R S).mkQ fun₀ | x + y => z) =
    ((KaehlerDifferential.kerTotal R S).mkQ fun₀ | x => z) + (KaehlerDifferential.kerTotal R S).mkQ fun₀ | y => z