no goals
α : Type u_1
β : Type ?u.178747
γ : Type ?u.178750
ι : Sort u_2
ι' : Sort ?u.178756
ι₂ : Sort ?u.178759
κ : ι → Sort ?u.178764
κ₁ : ι → Sort ?u.178769
κ₂ : ι → Sort ?u.178774
κ' : ι' → Sort ?u.178779
s : ι → Set (Set α)
⊢ (⋃₀ ⋃ (i : ι), s i) = ⋃ (i : ι), ⋃₀ s i
simp only [sUnion_eq_biUnion, biUnion_iUnion]