sub new {
    my ( $class, $param_hr ) = @_;
 
    my %self = (
        key            => 0,
        format         => 0,
        model          => 0,
        prettyprint    => 0,
        default_source => 0,
        default_target => 0,
        data_format    => 'perl',
        timeout        => 60,
        force_post     => 0,
        rest_url       => $REST_URL,
        agent          => ( sprintf '%s/%s', __PACKAGE__, $VERSION ),
        cache_file     => 0,
        headers        => {},
    );