Restore Apple Notes in Sierra and High Sierra

Super fast one. You lost your notes in the notes app. You have a backup (hopefully), here's where you go to retrieve them:

/Users/[youruserfolder]/Library/Group Containers/group.com.apple.notes

Simply copy the folder "group.com.apple.notes" from your backup to the same location on your Mac.
Boom, notes are back.
​You're welcome.