def provenance
      s = [rdf_uri, RDF::PROV.SoftwareAgent, @@agent]
      rdf.insert(s)
      s = [rdf_uri, RDF::PROV.generatedAtTime, rdf_now]
      rdf.insert(s)
    end
def provenance
      s = [rdf_uri, RDF::PROV.SoftwareAgent, @@agent]
      rdf.insert(s)
      s = [rdf_uri, RDF::PROV.generatedAtTime, rdf_now]
      rdf.insert(s)
    end
Assert PROV.SoftwareAgent and PROV.generatedAtTime