proposition: Lemma None_cput T (r : loc T) (s : coq_type T) e : nth_error e (loc_id r) = None -> cput r s e = fail.
proof: Proof. by move=> H; rewrite /cput H. Qed.
imports: JMeq mathcomp(all_ssreflect) mathcomp(finmap) mathcomp(classical_sets) monae_lib HB(structures) hierarchy monad_lib fail_lib state_lib trace_lib monad_transformer