Hi, thank you for the response! It was exactly what I wanted but how can I append the customer that is in the customer.csv file? customer.csv file: First name,Last name,Account number,Rented DVD list Jason,May,00001,[] Navis,Achero,00002,[Boston] Lexus,Baeng,00003,[] If Jason May wants to rent 'Hi', it should be appended in the 'Rented DVD list'. and also for the Navis it should be appended somehow like[Boston,Nope].

Lastly, for the DVD return, it will be the same process as DVD rent but it should be adding back again (original 3->rent 2->return back to 3)

First name, Last name, Account number, Rented DVD list Jason, May, 00001, [] Navis, Achero, 00002,[] Lexus, Baeng, 00003,[]