∀ {α : Type u_1} {β : Type u_2} [inst : Preorder α] [inst_1 : Preorder β] [inst_2 : LocallyFiniteOrder α]
  [inst_3 : LocallyFiniteOrder β] (a b x : α ⊕ β), x ∈ Finset.sumLift₂ Finset.Icc Finset.Icc a b ↔ a ≤ x ∧ x ≤ b