about showing all characters including non-printable, control etc

[Harry Putnam]

How can I make emacs show all the characters in a given line?

I've been using a little function that emulates vims :l cmd.
(That `:l' command in vim does show all characters in the current line)

I have two little home made defuns that do the job  sort of.
(defun vi-list ()
(defun vi-nolist ()

But that really needs to be a toggle of one function, and made to
apply to the line at point instead of the whole buffer.

Even better an existing emacs function that can be made to do this.