sub min_level{
    sub ($self,$min) = @_;

    $self->{params}->{min_level} = $min if defined $min;
    return $self->{params}->{min_level};
}

sub max_level{
    sub ($self,$max) = @_;

    $self->{params}->{max_level} = $max if defined $max;
    return $self->{params}->{max_level};
}

$file->min_level($new_min_level);
$file->max_level($new_max_level);