Proof using.
induction l; intros; simpl in *; intuition;
subst; break_match; intuition; subst; intuition.
Qed.
Ltac get_invariant i :=
match goal with
| H : refined_raft_intermediate_reachable _ |- _ =>
copy_apply i H
end.

(* Specifications: *)
Lemma in_not_nil :
forall A (l : list A) x,
In x l ->
l <> nil.