Override in subclasses to do bulk checks.

        Returns a sorted list.

        This is a conservative base implementation that brutally checks completeness, instance by instance.

        Inadvisable as it may be slow.

def missing_datetimes(self, finite_datetimes):
        """
        Override in subclasses to do bulk checks.

        Returns a sorted list.

        This is a conservative base implementation that brutally checks completeness, instance by instance.

        Inadvisable as it may be slow.
        """
        return [d for d in finite_datetimes if not self._instantiate_task_cls(self.datetime_to_parameter(d)).complete()]