my $aref = $matches{ $fasta_id }{ $sitekey };

my( $lo, $hi ) = ( 0, scalar @{ $aref } );
++$lo while $aref->[ $lo + 1 ] < $lowerlimit;
--$hi while $aref->[ $hi - 1 ] > $upperlimit;
                    
@{ $sets{ $fasta_id }[ $setscounter ]{ $sitekey } } =  @{ $aref }[ lo .. $hi ];