simp_all
case trans
α : Type u_1
a b : List α
f : α → Bool
hunique : ∀ (a1 a2 : α), f a1 = true → f a2 = true → a1 = a2
l₁✝ l₂✝ l₃✝ : List α
a✝¹ : l₁✝ ~ l₂✝
a✝ : l₂✝ ~ l₃✝
a_ih✝¹ : find? f l₁✝ = find? f l₂✝
a_ih✝ : find? f l₂✝ = find? f l₃✝
⊢ find? f l₁✝ = find? f l₃✝
no goals