fact: Definition append_zig_zag_of_length {C : category} {n m : ℕ} {x y z : C} (fs : zig_zag_of_length n x y) (gs : zig_zag_of_length m y z) : zig_zag_of_length (n + m) x z.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Groupoids