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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 refresh_token(self, **kwargs):
 """Refresh the authentication token. :param str refresh_token: The refresh token to use. May be empty if retrieved with ``fetch_token``. """

        if 'client_secret' not in kwargs:
            kwargs.update(client_secret=self.client_secret)
        if 'client_id' not in kwargs:
            kwargs.update(client_id=self.client_id)
        return self.session.refresh_token(token_url, **kwargs)