fact: Variable Hcomp : ∏ (x y z : C) a b c (f : C⟦x,y⟧) (g : C⟦y,z⟧), H a b f → H b c g → H a c (f · g).
imports: UniMath.Foundations.Sets UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Univalence UniMath.CategoryTheory.DisplayedCats.Core UniMath.CategoryTheory.DisplayedCats.Total UniMath.CategoryTheory.DisplayedCats.Isos UniMath.CategoryTheory.DisplayedCats.Univalence UniMath.CategoryTheory.DisplayedCats.Constructions