no goals
α : Type u
β : α → Type v
inst✝ : DecidableEq α
c : Sigma β
l : List (Sigma β)
h : NodupKeys (c :: l)
⊢ { entries := c :: l, nodupKeys := h } = insert c.fst c.snd { entries := l, nodupKeys := (_ : NodupKeys l) }
simpa [insert] using (kerase_of_not_mem_keys <| not_mem_keys_of_nodupKeys_cons h).symm