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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 set_temp_url_key(self, key=None):
 """ Sets the key for the Temporary URL for the account. It should be a key that is secret to the owner. If no key is provided, a UUID value will be generated and used. It can later be obtained by calling get_temp_url_key(). """

        if key is None:
            key = uuid.uuid4().hex
        meta = {"Temp-Url-Key": key}
        self.set_account_metadata(meta)
        self._cached_temp_url_key = key