Draws and ascii picture of a cons tree.
CL-USER> (draw-tree '(a b (c nil 1)))
[o|o]---[o|o]---[o|/]
| | |
A B [o|o]---[o|o]---[o|/]
| | |
C NIL 1
NIL
Ported from the function library of "Scheme 9 from Empty Space" http://www.t3x.org/s9fes/draw-tree.scm.html
Library is in the public domain in keeping with the original