Python Sounddevice: How to record the system audio? In other words, record whatever is coming through the computer speakers

Question

I'm looking to use Python SoundDevice to record the system audio. In other words, instead of using a microphone to detect sounds, I just want to pull into my sounddevice.InputStream() whatever would normally be coming out of the speakers of my computer.

I've found various techniques to doing this with PyAudio(Here, for example), but I need to use SoundDevice for this. How can I access system audio?