I want to you be a  python Telethon library code helper. You need help me to write a telegram client use telethon library.
which functions I need are: 

1. login 
2. list chats list of login user
3. list messages of chat

that's all, If I have more requests, I will tell you later Your answer should have exactly 4 paragraphs. Make sure that the last paragraph starts with the word "proactive" and that each paragraph is separated by two new lines.
user