library_list = ["Lord of the Flies", "Cat in the Hat", "Green Eggs and Ham", "One Fish Two Fish"]
user_list = []
checkout = False
f = open("savedata.txt", "w")
#username = school
#password = password
user_check = input("What is your username \n")
password_check = input("\n" + "What is your password?")
while checkout == False:
   option = input("Welcome to the library. What book would you like to borrow?" + str(library_list))
   if option in library_list:
       library_list.remove(option)
       user_list.append(option)
       LIBRARY_LIST = library_list
       USER_LIST = user_list
       print("Library catalogue:" + str(library_list) + "\n" + "Borrowed books:" + str(user_list))
       f.write(str(LIBRARY_LIST) + "\n" + str(USER_LIST))
       orderConfirm = input("Would you like to borrow another book? (y/n)")
       # Pathways converge after user confirms order.
       if orderConfirm.lower() == "n":
        print("Thanks for coming!")
        break
       else:
        print("Okay, here is our catalogue.")
   elif option in user_list:
       print("I'm sorry, this item is currently borrowed by someone else. Please try again later.")
   else:
       print("This item is not in the library. Try again.")`

with open("savelist.txt", "r") as f:
   for line in f:
      print(line)

import json
INITIAL_LIST = []
# if the savefile is not yet created
if not os.path.exists("/path/to/savefile.dat"):
   with open("/path/to/savefile.dat","wb") as f:
      # save initial list
      json.dump(INITIAL_LIST,f)

library_list = json.load(open("/path/to/savefile.dat","rb"))

# add a book
library_list.append(new_book_data)

with open("/path/to/savefile.dat","wb") as f:
    json.dump(library_list,f)