def register(self, user_id=None):
        if not user_id:
            user_id = calvinuuid.uuid("METERING")
        if user_id in self.users:
            raise Exception("User id already in use")
        self.users[user_id] = time.time()
        self.active = True
        return user_id
dataset/ETHPy150Open EricssonResearch/calvin-base/calvin/runtime/north/metering.py/Metering.register/original