Ever wanted to use 3rd party python libraries when making a Burp Extender? I had somehow avoided it until recently.
Warning: Be aware before pasting in the commands below that I think they configure your new pip environment and store all dependencies inside a new folder within the current directory.
In a nutshell it works like this:
java -jar jython-standalone-2.7.1.jar -m ensurepip
java -jar jython-standalone-2.7.1.jar -m pip install --upgrade pip
java -jar jython-standalone-2.7.1.jar -m pip install jsbeautifier
Making dependencies available in Burp
You need to configure the Python Environment on the “Extenders” -> “Options” tab as shown:

The second option needs to point to the folder where pip just initialised itself to. For me it was inside the BurpSuitePro folder as shown.
The source for this wizardry is the video below:
Happy Extender making you python wizards.