(*Prior to block := Z, the lemma as like this: Lemma find_symbol_add_globals: forall {F V} i g id dl, ~ In i (map fst dl) -> list_norepet (map fst dl) -> (Genv.find_symbol (Genv.add_globals (Genv.empty_genv F V) (dl ++ (i, g) :: nil)) id = Some (1 + Zlength dl) <-> i = id). *)

Lemma nth_error_rev:
forall T (vl: list T) (n: nat),
(n < length vl)%nat ->
nth_error (rev vl) n = nth_error vl (length vl - n - 1).