Inconsistent file extension handling for .txt files

Description:
If a user forgets to add .txt while reading, deleting, or creating a file, the program may not behave as expected. This leads to errors or duplicate files.

_Hint: Think about how the program could handle input when users enter a file name with or without the .txt extension._

Look for functions that read, delete, or create files, likely in the main script or a file handling module. The hint suggests normalizing file names to ensure .txt is appended when missing. Start by searching for file operations like open(), os.remove(), or os.path.exists(). Write a helper function to add .txt if absent, then apply it consistently. Test by running the program with and without the extension.

Written by the indexing model from the issue text.