code: protected function getRuleArgs($rule)
      {
          if (!$this->ruleHasArgs($rule)) {
              return [];
          }
  
          list($ruleName, $argsWithBracketAtTheEnd) = explode('(', $rule);
  
          $args = rtrim($argsWithBracketAtTheEnd, ')');
          $args = preg_replace('/\s+/', '', $args);
          $args = explode(',', $args);
  
          return $args;
      }
docs: Get rule arguments.
  
  @param  string $rule
  
  @return array