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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 decrypt_key(key, password):
 """ Decrypt an encrypted private key. :param key: Encrypted private key as a string. :param password: Key pass-phrase. :return: Decrypted private key as a string. """

    private = serialization.load_pem_private_key(key, password=password, backend=default_backend())
    return private.private_bytes(Encoding.PEM, PrivateFormat.PKCS8, NoEncryption())