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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 hmac_hex_key(self, hmac_hex_key):
 """ Sets the hmac_hex_key of this CfsslAuthCredentials. The key that is used to compute the HMAC of the request using the HMAC-SHA-256 algorithm. Must contain an even number of hexadecimal characters. :param hmac_hex_key: The hmac_hex_key of this CfsslAuthCredentials. :type: str """

        if hmac_hex_key is None:
            raise ValueError("Invalid value for `hmac_hex_key`, must not be `None`")
        if hmac_hex_key is not None and len(hmac_hex_key) > 64:
            raise ValueError("Invalid value for `hmac_hex_key`, length must be less than or equal to `64`")
        if hmac_hex_key is not None and not re.search('^([a-fA-F0-9][a-fA-F0-9]){1,32}$', hmac_hex_key):
            raise ValueError("Invalid value for `hmac_hex_key`, must be a follow pattern or equal to `/^([a-fA-F0-9][a-fA-F0-9]){1,32}$/`")

        self._hmac_hex_key = hmac_hex_key