class Stage(StageStep, ABC):
    """All Stages must inherit this base class."""

    # From the parent - just to showcase
    @abstractmethod
    def _run(self, record: Entity) -> Iterable[Either[str]]:
        """
        Main entrypoint to execute the step.

        Note that the goal of this step is to store the
        processed data somewhere (e.g., a file). We will
        return an iterable to keep track of the processed
        entities / exceptions, but the next step (Bulk Sink)
        won't read these results. It will directly
        pick up the file components.
        """