[plt-scheme] view procedure source code

Hi,

I'd like to know if there's a possibility in PLT scheme to get at a
procedure's source code?
Trying to understand the amb evaluator in SICP, I would like to print
out the success and failure continuations to see how exactly the
continuations are passed on / replaced (so the usual <procedure>
printout does not help).

Thanks a lot for your help!