my %small_hash;
@small_hash{@interesting_keys} 
    = @$config{@interesting_keys};
return \%small_hash;

##</code><code>##

# $config is given

sub get_file_watcher_ref {
    my %setting_for;
    my (
        $watch_interval,
        $watch_file_min_size,
        $term_run_time,
    );
    
    if ( $watch_interval = $config->{watch_interval} ) {
        $setting_for{watch_interval} = $watch_interval;
    }
    if ( $watch_file_min_size = $config->{watch_file_min_size} ) {
        $setting_for{watch_file_min_size} = $watch_file_min_size;
    }
    if ( $term_run_time = $config->{term_run_time} ) {
        $setting_for{term_run_time} = $term_run_time;
    }

    return \%setting_for;
}

##</code><code>##

sub get_file_watcher_ref {
    my %setting_for;
    my @interesting_keys = qw(
        watch_interval
        watch_file_min_size
        term_run_time
    );
    
    for (@interesting_keys) {
        if ($config->{$_}) $setting_for{$_} = $config->{$_};
    }
    
    return \%setting_for;
}