S9 LIB  (draw-tree object)  ==>  unspecific

Print a tree structure resembling a Scheme datum. Each cons
cell is represented by [o|o] with lines leading to their car
and cdr parts. Conses with a cdr value of () are represented
by [o|/].

(draw-tree '((a . b) (c d)))  ==>  unspecific

Output:  [o|o]---[o|o]--- ()
          |       |
          |      [o|o]---[o|o]--- ()
          |       |       |
          |       c       d
          |
         [o|o]--- b
          |
          a
