code: public static function valuesOf()
      {
          $enum   = new \ReflectionClass(get_called_class());
          $values = [];
          foreach ($enum->getStaticProperties() as $name => $instance) {
              $values[$name] = $instance->value;
          }
  
          return $values;
      }
docs: returns a list of values for given enum
  
  @api
  @return  mixed[]