Example of serializing a list using JSON.

json_example.py

import os
import json

FILE_PATH = './my_data.json'


def load_my_list():
    # If the file exists, open it and load our list
    # from the file at FILE_PATH.
    if os.path.exists(FILE_PATH):
        mylist = json.loads(open(FILE_PATH, 'rb').read())
    else:  # otherwise, initialize a new list.
        mylist = ['A','B','C']
    return mylist

def save_my_list(mylist):
    # Write a JSON dump of the list to FILE_PATH.
    # - A note of caution: this will overwrite whatever was
    # at that path.
    json.dump(mylist, open(FILE_PATH, 'wb'))


if __name__ == "__main__":
    my_list = load_my_list()
    print("Loaded my_list - my_list is: {0}".format(my_list))
    my_list.append('D')
    print("Appended 'D' - my_list is now: {0}".format(my_list))
    save_my_list(my_list)
    print("Saved my_list.")