rw [uniqueAux_acc_append_filter]
α : Type u_1
inst✝ : DecidableEq α
xs acc : List α
h : ∀ (x : α), x ∈ xs → ¬x ∈ acc
this : filter (fun a => decide ¬a ∈ acc) xs = xs
⊢ uniqueAux xs acc = reverse acc ++ unique xs
α : Type u_1
inst✝ : DecidableEq α
xs acc : List α
h : ∀ (x : α), x ∈ xs → ¬x ∈ acc
this : filter (fun a => decide ¬a ∈ acc) xs = xs
⊢ reverse acc ++ unique (filter (fun x => decide ¬x ∈ acc) xs) = reverse acc ++ unique xs