This CO2meter object is ripped from vfilimonov/co2meter, renamed to CO2meter (from CO2monitor). There's a bunch more docs over there (install docs, udev rules notes, monitoring server setup, etc), flask app, matplotlib plotter and other gadgets I didn't want.
https://github.com/vfilimonov/co2meter
I just wanted a tool to spit out json. I can import that into Splunk or whatever and make graphs in there.