Rotate curves around their endpoints

Good morning from Hamburg,
I have a set of curves in a row . I would like to rotate each of them around their endpoints at 90 degrees.
Sounds simple but I have no idea how to achieve that.
Any ideas for a newbie?

Thanks a lot in advance!
Guntherrotate curves.3dm (41.2 KB)

This is just one method. (12.6 KB)

Adam, thanks so much !!!