(** Environment operations. *)
(** The ternary predicate [binds] holds when a given binding is present somewhere in an environment. *)

(* Specifications: *)
Lemma binds_demo : forall (x:atom) (T:typ) (E F:env),
binds x T (E ++ (x ~ T) ++ F).
Lemma binds_demo : forall (x:atom) (T:typ) (E F:env),
binds x T (E ++ (x ~ T) ++ F).