{X Y : Type} (f : X -> Y) : plus_functor f o to_plus X == to_plus Y o f. Proof. intros x. unfold plus_functor, to_plus. refine (to_O_natural L (O_functor O f) (to O X x) @ _). apply ap. apply to_O_natural. Defined.
Require Import HoTT.Basics HoTT.Types. Require Import Extensions HFiber Truncations NullHomotopy Limits.Pullback. Require Import Descent Lex Separated.