apel software package provides portable library for emacsen, 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 apel
apel is installed in your system.
Make ensure the apel package were installed using the commands given below,
$ sudo dpkg-query -l | grep apel *
You will get with apel package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Editors |
| Package | apel |
| Version | 10.8+0.20120427-15 |
| Description | portable library for emacsen |
| Sub Section | Editors |