fact: Definition abses_codiagonal `{Funext} {A B : AbGroup} (E : AbSES B A) : AbSESMorphism (abses_direct_sum E E) E.
imports: Basics Types Truncations.Core Pointed.Core WildCat.Core Homotopy.ExactSequence AbGroups.AbelianGroup AbSES.Core AbGroups.Biproduct