(** ** Properties of [Forall] and [Forall2] *)

Lemma Forall2_cons_iff A B: forall P n h1 h2 (v1 : t A n) (v2 : t B n),
Forall2 P (h1 :: v1) (h2 :: v2) <-> P h1 h2 /\ Forall2 P v1 v2.