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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 access_token_response(self, token, message_id=None):
 """Access token response structure. Success if token is set, otherwise (None, empty string) give error response. If message_id is set then an extra messageId attribute is set in the response to handle postMessage() responses. """

        if (token):
            data = {"accessToken": token,
                    "expiresIn": self.access_token_lifetime}
            if (message_id):
                data['messageId'] = message_id
        else:
            data = {"error": "client_unauthorized",
                    "description": "No authorization details received"}
        return data