Function: visible-mode

Toggle making all invisible text temporarily visible (Visible mode).
With a prefix argument ARG, enable Visible mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.

This mode works by saving the value of `buffer-invisibility-spec'
and setting it to nil.

Variable: visible-mode

Non-nil if Visible mode is enabled.
Use the command `visible-mode' to change this variable.