public LoanCollection()
 {
     rw = new ReadAndWriteToFile<Loan>();
     loanCollection = new List<Loan>();
     fileName = "Loans.ser";
 }
 public PersonCollection()
 {
     rw = new ReadAndWriteToFile<Person>();
     personCollection = new List<Person>();
     fileName = "Persons.ser";
 }
 public BookCollection()
 {
     rw = new ReadAndWriteToFile<Book>();
     fileName = "Books.ser";
     bookCollection = new List<Book>();
 }