rfl
α : Type
inst✝¹ : (n : Nat) → OfNat α n
inst✝ : UInt α
x : α
⊢ (Fin.foldAll
        ((flip fun x mask => ((x.fst &&& ~~~mask) + (x.fst &&& mask) >>> x.snd, x.snd <<< 1)) ∘ fun i =>
          bitmask (OfNat.ofNat ↑i))
        (x, 1)).fst =
    (Fin.foldAll
        (fun i x =>
          ((x.fst &&& ~~~bitmask (OfNat.ofNat ↑i)) + (x.fst &&& bitmask (OfNat.ofNat ↑i)) >>> x.snd, x.snd <<< 1))
        (x, 1)).fst
no goals