code: def pbkdf2(seed: str or bytes, dk_len: int) -> bytes:
      
      key = b''
      index = 1
      bytes_seed = str_to_bytes(seed)
      while len(key) < dk_len:
          key += Digest.sha256(b''.join([bytes_seed, index.to_bytes(4, 'big', signed=True)]))
          index += 1
      return key[:dk_len]
docs: Derive one key from a seed.
  
      :param seed: the secret pass phrase to generate the keys from.
      :param dk_len: the length in bytes of every derived key.
      :return: