code: def _generate_AES_CBC_cipher(cek, iv):
      '''
      Generates and returns an encryption cipher for AES CBC using the given cek and iv.
  
      :param bytes[] cek: The content encryption key for the cipher.
      :param bytes[] iv: The initialization vector for the cipher.
      :return: A cipher for encrypting in AES256 CBC.
      :rtype: ~cryptography.hazmat.primitives.ciphers.Cipher
      '''
  
      backend = default_backend()
      algorithm = AES(cek)
      mode = CBC(iv)
      return Cipher(algorithm, mode, backendf _generate_AES_CBC_cipher(cek, iv):
      '''
      Generates and returns an encryption cipher for AES CBC using the given cek and iv.
  
      :param bytes[] cek: The content encryption key for the cipher.
      :param bytes[] iv: The initialization vector for the cipher.
      :return: A cipher for encrypting in AES256 CBC.
      :rtype: ~cryptography.hazmat.primitives.ciphers.Cipher
      '''
  
      backend = default_backend()
      algorithm = AES(cek)
      mode = CBC(iv)
      return Cipher(algorithm, mode, backend)
docs: Generates and returns an encryption cipher for AES CBC using the given cek and iv.
  
      :param bytes[] cek: The content encryption key for the cipher.
      :param bytes[] iv: The initialization vector for the cipher.
      :return: A cipher for encrypting in AES256 CBC.
      :rtype: ~cryptography.hazmat.primitives.ciphers.Cipher