proposition: Lemma insert_insert i s' s a : insert i s' (insert i s a) = insert i s' a.
proof: Proof. by apply boolp.funext => j; rewrite /insert; case: ifPn => // /negbTE ->. 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