public void checkoutBook(String memberID, String bookCopyId) {

    // Get Library member's FULL object from file System
    LibraryMember lm = libraryMemberService.readLibraryMember(memberID);

    //
    CheckoutRecord checkoutRecord = lm.getRecord();

    // Get BookCopy which we are trying to checkout
    BookCopy bookCopy = BookCopy.getBookCopy(bookCopyId);

    // Get the Book Object
    Book book = Book.get(bookCopy.getISBN());

    // Current/ today's date
    LocalDate checkoutDate = LocalDate.now();

    // Duedate = current date PLUS no of days to lend
    LocalDate dueDate = checkoutDate.plusDays(book.getDaysOfLend());

    // Create a new checkout entry
    CheckoutEntry checkoutEntry = new CheckoutEntry(bookCopy, checkoutDate, dueDate, false);

    checkoutRecord.addEntry(checkoutEntry);
    lm.setRecord(checkoutRecord);

    lm.writeLibraryMember(lm);
  }