choose-mirror software package provides Choose mirror to install from (menu item), 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 choose-mirror
choose-mirror is installed in your system.
Make ensure the choose-mirror package were installed using the commands given below,
$ sudo dpkg-query -l | grep choose-mirror *
You will get with choose-mirror package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | debian-installer udeb packages |
| Package | choose-mirror |
| Version | 2.73 |
| Description | Choose mirror to install from (menu item) |
| Sub Section | Debian-installer |