How Can I Split A CSV Into Separate .txt Files For Each Twitter User With All Their Tweets?

Hi everyone,
I have a CSV file where each row is a tweet, and each tweet has a user ID column (or username) and a text column. I’d like to create a separate .txt file for each user, with all their tweets combined in that file (one tweet per line).

Has anyone done this before? What’s the best way to do it in Python?

Any tips for cleaning up usernames or handling large datasets would also be appreciated. Thanks in advance!