code: def start(self):
          
          self._events_to_write = []
          self._new_contracts_to_write = []
  
          @events.on(SmartContractEvent.CONTRACT_CREATED)
          @events.on(SmartContractEvent.CONTRACT_MIGRATED)
          def call_on_success_event(sc_event: SmartContractEvent):
              self.on_smart_contract_created(sc_event)
  
          @events.on(SmartContractEvent.RUNTIME_NOTIFY)
          def call_on_event(sc_event: NotifyEvent):
              self.on_smart_contract_event(sc_event)
  
          Blockchain.Default().PersistCompleted.on_change += self.on_persist_completed
docs: Handle EventHub events for SmartContract decorators