docs: def decrypt_ecb(self, data):
      """
      Return an iterator that decrypts `data` using the Electronic Codebook (ECB)
      mode of operation.
      
      ECB mode can only operate on `data` that is a multiple of the block-size
      in length.
      
      Each iteration returns a block-sized :obj:`bytes` object (i.e. 8 bytes)
      containing the decrypted bytes of the corresponding block in `data`.
      
      `data` should be a :obj:`bytes`-like object that is a multiple of the
      block-size in length (i.e. 8, 16, 32, etc.).
      If it is not, a :exc:`ValueError` exception is raised.
      """
      S1, S2, S3, S4 = self.S
      P = self.P
      
      u4_1_pack = self._u4_1_pack
      u1_4_unpack = self._u1_4_unpack
      decrypt = self._decrypt
      
      u4_2_pack = self._u4_2_pack
      
      try:
        LR_iter = self._u4_2_iter_unpack(data)
      except struct_error:
        raise ValueError("data is not a multiple of the block-size in length")
      
      for cipher_L, cipher_R in LR_iter:
        yield u4_2_pack(
          *decrypt(cipher_L, cipher_R, P, S1, S2, S3, S4, u4_1_pack, u1_4_unpack)
        )