foo.pl

            my $dbx_acc = $opts->{dbxref_accession_prefix}.$propname;
            my $dbxref =
                $feature_prop_db->search( 'dbxrefs',
                                          { accession => $dbx_acc },
                                          { order_by => { -desc => ['version'] } }
                                        )
                                ->first
             || $feature_prop_db->create_related( 'dbxrefs', { accession => $dbx_acc,
                                                               version => 1,
                                                             });