(A B C : Type) `{In O C} : ooExtendableAlong (O_prod_unit A B) (fun _ => C). Proof. apply ooextendable_functor_prod. all:intros; rapply extendable_to_O. Defined.
Require Import HoTT.Basics HoTT.Types. Require Import Equiv.BiInv Extensions HProp HFiber NullHomotopy Limits.Pullback. Require Import Homotopy.IdentitySystems. Require Import Colimits.Pushout.