∀ {R : Type u_1} {S : Type u_2} [inst : NonUnitalNonAssocRing R] [inst_1 : NonUnitalNonAssocRing S] {F : Type u_3}
  [inst_2 : FunLike F R S] (f : F) [inst_3 : NonUnitalRingHomClass F R S] {I : TwoSidedIdeal S} {x : R},
  x ∈ (TwoSidedIdeal.comap f) I ↔ f x ∈ I