def METHOD_NAME(self, livesession, step):
    """scripts could be called simultaneously, we update reminders field
    using strict where clauses, the same ones used in the select query."""
    if livesession.reminders:
        livesession.reminders.append(step)
    else:
        livesession.reminders = [step]
    if livesession.must_notify and step in livesession.must_notify:
        livesession.must_notify.remove(step)
    # to send mails if still appropriate
    return (
        LiveSession.objects.filter(id=livesession.id, should_send_reminders=True)
        .exclude(
            reminders__overlap=[
                step,
                settings.REMINDER_ERROR,
            ]
        )
        .update(
            reminders=livesession.reminders, must_notify=livesession.must_notify
        )
    )