Flatten Nests Function in Lisp - need help understanding

Question

I\'ve been trying to find a way to condense nested lists into numbers that go back in the original list, but I having some trouble.

I\'ve been looking at the flatte

Answer 1

(defun flatten (l)

Above defines a function FLATTEN with one argument called L.

  (cond

IF

    ((null l) nil)

the value of the argument L is the empty list, return the empty list.

    ((atom l) (list l))

or if the argument L is an atom (i.e. not a list), then return a list with the atom as its only item.

    (t 

or else we have a non-empty list

       (loop for a in l

then loop through all the items in the list which is the value of L

        appending (flatten a)

and append the results of flattening each list item.

))))