case _ h => simp [←h]
α : Sort u_1
β : Type u_2
f : α ⇀ β
a : α
opt✝ : Option { b // ∃ a, f a = some b }
x✝ : { b // ∃ a, f a = some b }
b✝ : β
heq✝ : f a = some b✝
h : { val := b✝, property := ⋯ } = x✝
⊢ ↑x✝ = b✝
no goals