用python写的命令行电话薄程序

最近读完了《A Byte of Python》，按照书上提示写了一个命令行电话薄程序(与书上要求相比略有缩减)。

程序比较糙，希望看到的大神能够不吝赐教……

以下是源代码

#Filename: AddressBook.py

import pickle

class AddressBook:
    
    filename = ''
    
    def __init__(self, name, phone):    #initialize class
        self.name = name
        self.phone = phone
        self.personlist = {name : phone}
    def add(self):                      #add item
        name = input('Enter a name: ')
        if name in self.personlist.keys():
            print('The name is already existing!')
        else:
            phone = input('Enter a phone number: ')
            self.personlist[name] = phone
            print('Saved!')
    def modify(self):                   #modify item
        name = input('Enter a name: ')
        if name not in self.personlist.keys():
            print('Failure! The name not here: ')
        else:
            phone = input('Enter a new phone: ')
            self.personlist[name] = phone
            print('Modify successfully!')
    def delete(self):                   #delete item
        name = input('Enter a name: ')
        if name not in self.personlist.keys():
            print('The name is not here.')
        else:
            self.personlist.__delitem__(name)
            print('Delete successfully!')
    def search(self):                   #search item
        name = input('Enter a name: ')
        if name not in self.personlist.keys():
            print('The name is not here.')
        else:
            print('Name: {0}, Phone: {1}' .format(name, self.personlist[name]))
    def show(self):                     #show items
        for name in self.personlist.keys():
            print('Name: {0}  Phone: {1}' .format(name, self.personlist[name]))
    def dump(self):                     #dump data to disc
        filename = self.name + '.data'
        f = open(filename, 'wb')
        pickle.dump(self.personlist, f)
        f.close()
    def load(self):                     #load data from disc
        filename = self.name + '.data'
        f = open(filename, 'rb')
        self.personlist = pickle.load(f)
        f.close()
if __name__ == '__main__':
    
    command = ['add','modify','search','delete','quit' ,'show']
    person = AddressBook('hahaha', 123456789)

    ans = input("Do you want to load existing data from disc?(Y/N)")
    if ans == 'Y':
        person.load()

    while True:
        str = input('What are you going to do(add/modify/search/delete/show/quit)?')

        if str in command:
            if str == 'add':
                person.add()
            elif str == 'modify':
                person.modify()
            elif str == 'search':
                person.search()
            elif str == 'delete':
                person.delete()
            elif str == 'show':
                person.show()
            else:
                answer = input("Your contacts list hasn't  been saved,save it now?(Y/N)")
                if answer == 'Y':
                    person.dump()
                    print('Dump successfully!')
                else:
                    print ('Exit the System')
                break
        else:
            print ('Please input the command!')
    

这个程序使用Wing IDE写的，不知道为什么不能写中文注释，有哪位知道原因能不能给说明下，先谢谢了。