With ARG, turn Hl-Line mode on if ARG is positive, off otherwise.
Uses functions `hl-line-unhighlight' and `hl-line-highlight' on
`pre-command-hook' and `post-command-hook'."
+ nil nil nil
(if hl-line-mode
(progn
(add-hook 'pre-command-hook #'hl-line-unhighlight)