public Person(string firstName, string lastName,
     string password, HashSet<PersonGroup> personGroups)
 {
     this.id = curCount;
     curCount++;
     this.firstName = firstName;
     this.lastName = lastName;
     this.password = password;
     card = new Card();
     card.SetPersonID(ID);
     this.personGroups = personGroups;
 }
 public Person IdentifyPerson(Card c)
 {
     return DBUserInterface.Instance.GetPerson(c.GetPersonID());
 }