$loglevel = 2; # should be set by getopt
sub loglevel {
    my $data =  shift;
    return $data->[1] <= $loglevel ? Dumper $data->[0] : "";
}

# ... Insert some code here.

$log->format(\&loglevel);
$log->entry( [$some_ref, 1] );

$log->entry("We always log this!", 'standard' );  # Sticks a time and date stamp in front of text.