no goals
α : Type u_1
β : Type ?u.22430
R : Type ?u.22433
R' : Type ?u.22436
ms : Set (OuterMeasure α)
m✝ m : OuterMeasure α
s₁ s₂ : Set α
h₁ : ↑m s₁ = 0
h₂ : ↑m s₂ = 0
⊢ ↑m (s₁ ∪ s₂) = 0
simpa [h₁, h₂] using m.union s₁ s₂