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