Iterating through a Spira repo?

Hi.

I have a file with a few dozen N-Triples, describing three or four subjects
(entities), with several predicate for each.  I use Spira and rdf.rb.  I'd
like to *iterate* over all the different subjects in the repo, to present
all of them, without knowing their URIs in advance.  In my sample, they are
all of the form <http://..../ItemNNN>, so I could construct these URLs for
my sample, but more generally, I wouldn't know what entities are there.

So is there a way to enumerate the entities in a repo?

Thanks in advance,

   Asaf
-- 
Asaf Bartov <asaf.bartov@gmail.com>