fact: Definition right_cons_zig_zag {C : category} {x z y : C} (f : z --> x) (gs : zig_zag z y) : zig_zag x y := 1 + length_of_zig_zag gs ,, (z ,, (inr f ,, pr2 gs)).
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Groupoids