def add_holding_event(self, event: Event) -> None:
        """
        Add an event to the list of those collected in current step.

        This is only relevant for stepwise execution.
        """
        if self.stepwise:
            if self._step_events_holding is None:
                self._step_events_holding = []

            self._step_events_holding.append(event)

        Add an event to the list of those collected in current step.

        This is only relevant for stepwise execution.
        
llama-index-core/llama_index/core/workflow/context.py