my @res;
my $i = 0;
while( $i < $#tally ) {
    ++$i until defined $tally[ $i ];
    my $val = $tally[ $i ];
    my $start = $i;
    ++$i while defined( $tally[ $i ] ) and $tally[ $i ] == $val;
    my $end = $i - 1;
    push @res, [ int2dhm( $start ), int2dhm( $end ), $val ];
}