TIMTOWTDY... ;-)

# file Secs.pm
package Secs;
use base Math::BigInt;

use overload '""' => \&as_string, fallback => 1;

sub as_string {
    my $h = int $_[0]/3600;
    my $m = int(($_[0]-$h*3600)/60);
    sprintf "%d:%02d:%02d",$h,$m,$_[0]-$h*3600-$m*60;
}
1;
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use Secs;

print Secs->new($end - $start),"\n";
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