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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 passphrase(self, passphrase):
 """ Sets the passphrase of this GlobalSignCredentials. The passphrase to decrypt the private key in case it is encrypted. Empty if the private key is not encrypted. :param passphrase: The passphrase of this GlobalSignCredentials. :type: str """

        if passphrase is not None and len(passphrase) > 1000:
            raise ValueError("Invalid value for `passphrase`, length must be less than or equal to `1000`")

        self._passphrase = passphrase