/// <summary>
/// Function to retrieve filtered list of persons.
/// </summary>
/// <param name="persons">Instance of Persons</param>
/// <param name="personIdentityList">List of person identities</param>
/// <returns>Instance of Persons containing filtered persons</returns>
internal static Person RetrieveFilteredPersons(this Person persons, IList<PersonIdentity> personIdentityList)
{
Person filteredPersons = new Person();
filteredPersons.AssignGuests(persons.Guests.RetrieveMatchingGuests(personIdentityList));
filteredPersons.AssignCrewmembers(persons.Crewmembers.RetrieveMatchingCrewmembers(personIdentityList));
filteredPersons.AssignVisitors(persons.Visitors.RetrieveMatchingVisitors(personIdentityList));
return filteredPersons;
}