...
    print "\nAnd here comes the result of sorting the keys of that hash\n";

    my $sort_function = ($demo eq 'problem')          ? 
                         sub { $distance{$b}->value <=>
                               $distance{$a}->value } :
                         sub { $distance{$b}        <=>
                               $distance{$a} };

    for my $place (sort $sort_function keys %distance)
    {
        printf "%10s is %25.15f km from here\n", $place, $distance{$place};
    }
}