hexchat-python3 software package provides Python 3 plugin for HexChat, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install hexchat-python3
hexchat-python3 is installed in your system.
Make ensure the hexchat-python3 package were installed using the commands given below,
$ sudo dpkg-query -l | grep hexchat-python3 *
You will get with hexchat-python3 package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Network |
| Package | hexchat-python3 |
| Version | 2.12.0-2+b1 |
| Description | Python 3 plugin for HexChat |
| Sub Section | Net |