(** Correctness of the [starts_with] test. *)

Lemma starts_with_correct:
forall lbl c1 c2 c3 s f sp ls m,
is_tail c1 c2 ->
unique_labels c2 ->
starts_with lbl c1 = true ->
find_label lbl c2 = Some c3 ->
plus step tge (State s f sp c1 ls m)
E0 (State s f sp c3 ls m).