∀ {S : Type u_2} {A : Type u_1} [inst : NonUnitalNonAssocSemiring A] [inst_1 : SetLike S A]
  [inst_2 : NonUnitalSubsemiringClass S A] (s : S) (x y : ↥s),
  (NonUnitalSubsemiringClass.subtype s).toFun (x * y) =
    (NonUnitalSubsemiringClass.subtype s).toFun x * (NonUnitalSubsemiringClass.subtype s).toFun y