Neat. It might be interesting to try this with DrScheme, since it can display images inline in the repl.
That section is based on the same original paper, and it is very nice to check on the book's explanation using a modern environment such as DrScheme.
[1] http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-15.html...
[2] http://planet.plt-scheme.org/package-source/soegaard/sicp.pl...
[3] http://planet.plt-scheme.org/display.ss?package=sicp.plt&...