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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 request_access_token(self, params):
 """ Request the access token from `self.access_token_url`. The default behaviour is to use a `POST` request, but some services use `GET` requests. Individual clients can override this method to use the correct HTTP method. """

        return self.request(self.access_token_url, method="POST", params=params,
            is_signed=False)