backup and restore with duplicity

Duplicity backup utility is the old workhorse in all recent Ubuntu versions. I use the GUI called Deja-Dup for quite a while now. But until now I never bothered to check how to restore my files. I did decide to check how to restore file, because backup is only half the job! It turns out, that the GUI does a disservice for duplicity users. Restoring an encrypted backup turned out to not work. I didn't bother to research why, and turned to the CLI. This is a reminder on how to restore the files.