Python pickle序列化后写入文件，并实现曾加内容

# _*_coding:utf-8_*_
import pickle
import os

list_ec = []

while True:
    if os.path.isfile("course_list"):    # 判断文件夹是否存在
        with open("course_list", "rb") as f:
            list_aa = pickle.load(f)
            f.close()
        # print(list_aa)    # 可以打开，每次读取完文件的时候，打印出来
        nu = input(">>")    # 输入列表内每个元素的首字符以"|"为分割符
        if nu == "exit":
            break
        else:

            for i in list_aa:
                list_ec.append(i)
                if nu == i.split("|")[0]:
                    number_a = list_aa.index(i)
                    # print(number_a)    # 打印出每次修改元素所在列表内的索引
            ni = input(">:")    # 输入增加的字符
            nui = list_ec[number_a]
            list_ec[number_a] = "%s|%s" % (nui, ni)
            print(list_ec)    # 输入完成后，打印出修改完成的字符
            with open("course_list", "wb") as f:
                pickle.dump(list_ec, f)
                f.close()
    else:
        """
        文件夹不存在先把下面的信息写入创建文件的夹内
        """
        a = "Lili|python|linux"
        b = "admin|linux|python"
        c = "ak|python|go"
        list_a = [a, b, c]
        print(list_a)
        with open("course_list", "wb") as f:
            pickle.dump(list_a, f)
            f.close()

C:\Python35\python.exe C:/Users/pengi/Desktop/6-13/class_s.py
[‘Lili|python|linux‘, ‘admin|linux|python‘, ‘ak|python|go‘]
>>ak
>:linux
[‘Lili|python|linux‘, ‘admin|linux|python‘, ‘ak|python|go|linux‘]