Definition nattrans_nattrans_arrow_assoc {C:category} {c:C} {X X' X'':[C^op,HSET]} (x:c⇒X) (p:X-->X') (q:X'-->X'') : q ⟳ (p ⟳ x) = (q ∘ p) ⟳ x := idpath _.
Require Import UniMath.MoreFoundations.Tactics.