fact: Definition equiv_indecomposable_sum {X A B} `{Indecomposable X} (f : X <~> A + B) : ((X <~> A) * (Empty <~> B)) + ((X <~> B) * (Empty <~> A)).
imports: HoTT.Basics Types.Empty Types.Unit Types.Prod Types.Sigma Types.Bool Types.Forall