fact: Definition O_functor_compose {A B C : Type} (f : A -> B) (g : B -> C) : (O_functor (g o f)) == (O_functor g) o (O_functor f).
imports: HoTT.Basics HoTT.Types Equiv.BiInv Extensions HProp HFiber NullHomotopy Limits.Pullback PathAny Colimits.Pushout