Call::mapClientMark

private function mapClientMark(int $callVote): ?string
{
	switch ($callVote)
	{
		case StatisticsMark::Negative:
			return ClientMark::NEGATIVE;
		case StatisticsMark::Neutral:
			return ClientMark::NEUTRAL;
		case StatisticsMark::Positive:
			return ClientMark::POSITIVE;
		default:
			return null;
	}
}