Simple command-line tool to change screen brightness, can be used in conjunction with keyboard shortcut.
$ git clone https://github.com/herrfz/brightness
$ cd brightness
$ pip install .
Then simply brightness inc and brightness dec.
To use as a keyboard shortcut, e.g. via obkey, it may be required to include in $PATH, or add a symlink:
$ sudo ln -s $(which brightness) /usr/bin/brightness