How do I save a node tree to use on all projects?

How do I save a node tree, albeit an empty one, as a preset to use on all other projects?
https://forum.blackmagicdesign.com/
https://forum.blackmagicdesign.com/viewtopic.php?f=21&t=136069
Jim Robinson wrote:convert Still to powergrade.
capthook wrote:Jim Robinson wrote:convert Still to powergrade.
Even easier - nice Jim!
If you open up the additional panel in the Gallery Viewer, you get 3 'folders'.
One of those is PowerGrade.
If you just drag a thumbnail from the Gallery Viewer while in Still view into the PowerGrade folder, it will save it there.
Then in PowerGrade view, you can apply the grade to a clip.
No need for export/import!