[plt-scheme] HTDP 16.3.4

I am looking at the last part of the section marked Challenge which requires 
a function

;;func-producing-list-of-lists: symbol directory-structure -> [[symbol]]
;;produces a list of all the paths to files of the specified name in the 
directory structure.

I've  not been able to figure how to continue to generate paths after 
finding the first one ..... well thats not quite true but I presume removing 
entries from the directory so that the basic find function selects a 
different path on each invocation isn't what is sought for here.