proposition: Lemma isunit_setofendabgr_un1 {G : abgr} : isunit (@ringofendabgr_op2 G) setofendabgr_un1.
proof: Proof. exact (make_isunit islunit_setofendabgr_un1 isrunit_setofendabgr_un1). Defined.
imports: UniMath.MoreFoundations.Tactics UniMath.Algebra.RigsAndRings UniMath.Algebra.Groups UniMath.Algebra.Monoids