public Models.Person Build()
        {
            var person = new Models.Person(FirstNameState.Get(), LastNameState.Get());

            foreach (var contact in Contacts)
            {
                person.Add(contact);
            }
            person.SetPrimaryContact(PrimaryContact.Get());
            return(person);
        }
 public IPrimaryContactHolder WithLastName(string lastName)
 {
     LastNameState = LastNameState.Set(lastName);
     return(this);
 }