Programmatically get Plex Main Folder?

Forgive me if this is already documented somewhere. If so, I would ask to be pointed in that direction.

Given this snippet of information:

* '%LOCALAPPDATA%\Plex Media Server\'                                        # Windows Vista/7/8
* '%USERPROFILE%\Local Settings\Application Data\Plex Media Server\'         # Windows XP, 2003, Home Server
* '$HOME/Library/Application Support/Plex Media Server/'                     # Mac OS
* '$PLEX_HOME/Library/Application Support/Plex Media Server/',               # Linux
* '/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/', # Debian,Fedora,CentOS,Ubuntu
* '/usr/local/plexdata/Plex Media Server/',                                  # FreeBSD
* '/usr/pbi/plexmediaserver-amd64/plexdata/Plex Media Server/',              # FreeNAS
* '${JAIL_ROOT}/var/db/plexdata/Plex Media Server/',                         # FreeNAS
* '/c/.plex/Library/Application Support/Plex Media Server/',                 # ReadyNAS
* '/share/MD0_DATA/.qpkg/PlexMediaServer/Library/Plex Media Server/',        # QNAP
* '/volume1/Plex/Library/Application Support/Plex Media Server/',            # Synology, Asustor
* '/raid0/data/module/Plex/sys/Plex Media Server/',                          # Thecus
* '/raid0/data/PLEX_CONFIG/Plex Media Server/'                               # Thecus Plex community

What would be a recommended way to programmatically get the Plex Main Folder location?

Is there an environment variable I can inspect or something? Or do I need to query the os/platform and determine this manually?

Just doing my googles and I stumbled across this.

%PLEX_PATH%

Is that a thing?