Where I can assign a default class/selector to this custom element?
<?php 
// element-test.php
if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly
class Prefix_Element_Test extends \Bricks\Element {
  // Element properties
  public $category     = '';
  public $name         = '';
  public $icon         = '';
  public $css_selector = '';
  public $scripts      = [];
  public $nestable     = false; // true || @since 1.5
  // Methods: Builder-specific
  public function get_label() {}
  public function get_keywords() {}
  public function set_control_groups() {}
  public function set_controls() {}
  // Methods: Frontend-specific
  public function enqueue_scripts() {}
  public function render() {}
}
            