simp [encode, inst.decode_fin_is_some (Nat.fin_mod _ _)]
α : Type u_1
inst : Alphabet α
n : ℕ
ih : encode (decode (n / Fintype.card α)) = n / Fintype.card α
⊢ encode (Option.get (Encodable.decode ↑(Nat.fin_mod n ⋯)) ⋯ :: decode (n / Fintype.card α)) = Nat.succ n
α : Type u_1
inst : Alphabet α
n : ℕ
ih : encode (decode (n / Fintype.card α)) = n / Fintype.card α
⊢ encode (decode (n / Fintype.card α)) * Fintype.card α +
      Encodable.encode (Option.get (Encodable.decode ↑(Nat.fin_mod n ⋯)) ⋯) =
    n