lisp-indent-line

[A Soare]

(defun new-lisp-indent-line (&optional whole-exp)
  "Indent current line as Lisp code.
With argument, indent any additional lines of the same expression
rigidly along with this one."
  (interactive "P")
  ...)



lisp-indent-line has one parameter.

However, it is never used in the code as far as I see... I do not understand 
its logic...

Can somebody explain me its logic , please?

what means that: "With argument, indent any additional lines of the same 
expression rigidly along with this one." ?

Is it an important feature that worth to be kept in future?

a soare.