A slightly modified version of the PowerShell lexer from the Pygments highlighter.
To install the file shell.py, go to your local Python installation folder (it is assumed that the Pygments have been already installed) and simply place the file in the following sub-folder:
%installation-folder%\Lib\site-packages\pygments\lexers
Ensure that everything is up-to-date as regards the lexers by running the following command from the terminal:
python _mapping.py