∀ {ι : Type u_1} {M : Type u_3} [inst : Add M] [inst_1 : Preorder M] [AddLeftMono M] [AddRightMono M] {f g : ι → M},
  BddBelow (Set.range f) → BddBelow (Set.range g) → BddBelow (Set.range fun i => f i + g i)