/* isp RemoveFormation() * * Input variables: * battleFormation = * * State variables: * * */ public void RemoveFormation(BattleFormation battleFormation) { if (battleFormation is null) { throw new ArgumentNullException(nameof(BattleFormation)); } var formations = Formations.Where(f => f.Equals(battleFormation)); if (formations == null || formations.Count() == 0) { throw new ArgumentException("Battle formation does not exist"); } Formations.Remove(battleFormation); }