def METHOD_NAME(issue, field=None):
    users = []
    qs_filter = Q()
    if field == 'responsible':
        qs_filter = Q(id=issue.responsible_id)
    elif field == 'followers':
        qs_filter = Q(id__in=issue.followers.all().values_list("id", flat=True))
    elif field == 'costudents':
        for user in issue.task.course.get_students():
            users.append((user.id, user.get_full_name()))
        return users
    for user in User.objects.filter(Q(is_staff=True) | Q(course_teachers_set=issue.task.course) | qs_filter).distinct():
        users.append((user.id, user.get_full_name()))
    return users