proposition: Lemma Derive_n_correct f n x : ex_derive_n f n x -> is_derive_n f n x (Derive_n f n x).
proof: Proof. case: n => /= [ | n] Hf. by []. by apply Derive_correct. Qed.
imports: Coq(Reals Psatz ssreflect) Rcomplements Rbar Lim_seq Iter Hierarchy Continuity Equiv