fact: Definition cochain_mor {C : category} (c : cochain C) {i j} : i < j -> C⟦dob c j, dob c i⟧.
imports: UniMath.Foundations.PartA UniMath.CategoryTheory.Core.Categories UniMath.Foundations.NaturalNumbers UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Limits.Graphs.Colimits UniMath.CategoryTheory.Limits.Graphs.Limits UniMath.CategoryTheory.Limits.Terminal