sub count_in_array {
    my $num_ints = $_[0] // $datasize;
    my @container;
    $container[ rand_ranged_value( 1, 999 ) ]++ 
        for( 1 .. $num_ints );
    return {    # Anonymous hash constructor.
        map{ 
                $container[$_] > 0 
                    ? ( $_ => $container[$_] ) 
                    : () 
        } 1 .. $#container
    };
}