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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 authorization_code(self, code, redirect_uri):
 """ Retrieve access token by `authorization_code` grant. https://tools.ietf.org/html/rfc6749#section-4.1.3 :param str code: The authorization code received from the authorization server. :param str redirect_uri: the identical value of the "redirect_uri" parameter in the authorization request. :rtype: dict :return: Access token response """

        return self._token_request(grant_type='authorization_code', code=code,
                                   redirect_uri=redirect_uri)