(** Composition *)

Lemma Lim_comp (f g : R -> R) (x : Rbar) :
ex_lim f (Lim g x) -> ex_lim g x -> Rbar_locally' x (fun y => Finite (g y) <> Lim g x)
-> Lim (fun x => f (g x)) x = Lim f (Lim g x).