fact: Definition append_zig_zag {C : category} {x y z : C} (fs : zig_zag x y) (gs : zig_zag y z) : zig_zag x z := length_of_zig_zag fs + length_of_zig_zag gs ,, append_zig_zag_of_length (pr2 fs) (pr2 gs).
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Groupoids