This place is for issues with the library, so please make sure that:
1. The error is in the library's code, and not in your own.
2. You have already searched for your error on existing issues.
3. You are testing with upstream code (pip install -U https://github.com/LonamiWebs/Telethon/archive/master.zip).
If you have a question, ask in the official Telegram group https://t.me/TelethonChat or https://stackoverflow.com. Enhancement ideas are currently welcome, too.