private static bool FieldIsSelf(Fighter fighter, Position fieldCell)
{
if (fighter.Head != null && fighter.Head.X == fieldCell.X && fighter.Head.Y == fieldCell.Y) return true;
if (fighter.Tail != null && fighter.Tail.X == fieldCell.X && fighter.Tail.Y == fieldCell.Y) return true;
return fighter.Body.Any(b => b.X == fieldCell.X && b.Y == fieldCell.Y);
}
}