my @sorted =
    map  { $_->[0] }
    sort { $a->[1] <=> $b->[1] || $a->[2] cmp $b->[2] }
    map  { my $s = $_->seq_region_name;
           [ $_, $s =~ m/^[0-9]+$/ ? $s : 999, $s ]
           }
    @unsorted;