elpa-rainbow-delimiters software package provides Emacs mode to colour-code delimiters according to their depth, 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-rainbow-delimiters
elpa-rainbow-delimiters is installed in your system.
Make ensure the elpa-rainbow-delimiters package were installed using the commands given below,
$ sudo dpkg-query -l | grep elpa-rainbow-delimiters *
You will get with elpa-rainbow-delimiters package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Lisp |
| Package | elpa-rainbow-delimiters |
| Version | 2.1.3-1 |
| Description | Emacs mode to colour-code delimiters according to their depth |
| Sub Section | Lisp |