sub browser2 {
    my %count;

    $count{ A } = $seq =~ tr[A][A];
    $count{ C } = $seq =~ tr[C][C];
    $count{ G } = $seq =~ tr[G][G];
    $count{ T } = $seq =~ tr[T][T];

    for( qw'AA AC AG AT CA CC CG CT GA GC GG GT TA TC TG TT' ) {
        my $p=0;
        $count{ $_ }++ while $p = 1+index $seq, $_, $p;
    }

    for( qw[
        TTT TTG TTC TTA TGT TGG TGC TGA TCT TCG TCC TCA TAT TAG TAC TAA
        GTT GTG GTC GTA GGT GGG GGC GGA GCT GCG GCC GCA GAT GAG GAC GAA
        CTT CTG CTC CTA CGT CGG CGC CGA CCT CCG CCC CCA CAT CAG CAC CAA
        ATT ATG ATC ATA AGT AGG AGC AGA ACT ACG ACC ACA AAT AAG AAC AAA
    ] ) {
        my $p=0;
        $count{ $_ }++ while $p = 1+index $seq, $_, $p;
    }
    1;
}