/**
  * Creates or returns an instance of this class.
  * @since  0.1.0
  * @return WDS_CMB2_Date_Range_Field A single instance of this class.
  */
 public static function get_instance()
 {
     static $instance = null;
     if (null === $instance) {
         $instance = new self();
     }
     $instance->hooks();
     return $instance;
 }