case nil=> intros; rfl
α : Type u
r : α → α → Prop
inst✝¹ : StrictLinearOrder r
inst✝ : DecidableRel r
β : α → Type v
f : (a : α) → β a → β a → Option (β a)
a : α
b : β a
ys : KVChain r β
⊢ ∀ (xs : KVChain r fun a => β a) (haxs : boundLeft a xs) (hays : boundLeft a KVChain.nil),
    mergeWith f (KVChain.cons a b xs haxs) KVChain.nil =
      KVChain.cons a b (mergeWith f xs KVChain.nil) (_ : boundLeft a (mergeWith f xs KVChain.nil))
no goals