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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

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, backend)