private void CheckExtensions(IEnumerable <Extension> extensions)
{
_missingExtensions.AddIf(extensions, ex => ex.level > _characterExtensions.GetLevel(ex.id));
}
public static void AddIfNotIn <T>(this HashSet <T> Lst, T Element, IEnumerable <T> ExclusionList)
{
Lst.AddIf(Element, E => !ExclusionList.Contains(E));
}