cl-rotatef
cl-rotatef is an autoloaded Lisp macro in `cl-macs.el
'.
(cl-rotatef PLACE...)
Rotate left among PLACEs.
Example: (cl-rotatef A B C) sets A to B, B to C, and C to A. It returns nil.
Each PLACE may be a symbol, or any generalized variable allowed by `setf'.