public function install()
{
    try {
        $expressObject = Express::getObjectByHandle('my_category');
        if (is_object($expressObject)) {
            Express::deleteEntry($expressObject);
        } 
        $expressObject = Express::buildObject('my_category', 'my_categories', 'My Category', $pkg);
        $expressObject->addAttribute('text', 'My Category Name', 'my_category_name');
        $expressObject->save();
 
        $form = $expressObject->buildForm('Form');
        $form->addFieldset('Basics')
            ->addAttributeKeyControl('my_category_name');
        $form = $form->save();
 
        $expressObject->getEntity()->setDefaultViewForm($form);
        $expressObject->getEntity()->setDefaultEditForm($form);
        $expressObject->save();
 
        return true;
    }
 
    catch (\Exception $err) {
        return false;
    }
}
 
public function uninstall()
{
    $expressObject = Express::getObjectByHandle('my_category');
    if(is_object($expressObject)) {
        Express::deleteEntry($expressObject);
    }
}