proposition: Lemma lc_exp_of_lc_set_exp_mutual : (forall e1, lc_set_exp e1 -> lc_exp e1).
proof: Proof. apply_mutual_ind lc_set_exp_mutind; default_simp. Qed.
imports: Coq.Logic.FunctionalExtensionality Coq.Program.Equality Metalib.Metatheory Metalib.LibLNgen Stlc