def timeline(self, request, drip_id, into_past, into_future):
        """
        Return a list of people who should get emails.
        """
        from django.shortcuts import render, get_object_or_404

        drip = get_object_or_404(Drip, id=drip_id)

        shifted_drips = []
        seen_users = set()
        for shifted_drip in drip.drip.walk(into_past=int(into_past), into_future=int(into_future)+1):
            shifted_drip.prune()
            shifted_drips.append({
                'drip': shifted_drip,
                'qs': shifted_drip.get_queryset().exclude(id__in=seen_users)
            })
            seen_users.update(shifted_drip.get_queryset().values_list('id', flat=True))

        return render(request, 'drip/timeline.html', locals())
Return a list of people who should get emails.