public static bool IsPersonNotEmpty(Person person)
 {
     if (person.FirstName != null && person.LastName != null && person.Age != 0 && person.Pesel != null && person.PhoneNumber != null)
     {
         return true;
     }
     return false;
 }           
 public void AddPerson(Person person)
 {
     List<Person> persons = GetAllPersons();
     if (File.Exists(path))
     {                
         persons.Add(person);
         XMLSerializer.Serialization(persons, path);
     }
     else
     {
         persons.Add(person);
         XMLSerializer.Serialization(persons, path);
     }
 }
 private Person ConsoleRead() 
 {
     Person personView = new Person();
    
     Console.WriteLine("Podaj imię: ");
     personView.FirstName = Console.ReadLine();
     Console.WriteLine("Podaj nazwisko: ");
     personView.LastName = Console.ReadLine();
     Console.WriteLine("Podaj wiek: ");
     personView.Age = int.Parse(Console.ReadLine());
     Console.WriteLine("Podaj pesel: ");
     personView.Pesel = Console.ReadLine();
     Console.WriteLine("Podaj nr telefonu: ");
     personView.PhoneNumber = Console.ReadLine();
             
     return personView;
 }