elpa-company software package provides Modular in-buffer completion framework for Emacs, 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 elpa-company
elpa-company is installed in your system.
Make ensure the elpa-company package were installed using the commands given below,
$ sudo dpkg-query -l | grep elpa-company *
You will get with elpa-company package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Lisp |
| Package | elpa-company |
| Version | 0.8.12-4 |
| Description | Modular in-buffer completion framework for Emacs |
| Sub Section | Lisp |