corner-bb
and
rcross-bb
which should look like their counterparts in figure 1.4 on page 16 of the
text. Then
my-bb
should show your invented basic block.
(pinwheel (pinwheel (pinwheel rcross-bb)))
which should show a large version of the repeating crosses pattern shown
on page 15, and
(pinwheel (pinwheel (pinwheel my-bb)))
to see what sort of quilt pattern your basic block generates.