code: public function usersOfTag($tagId, $nextOpenId = '')
      {
          $params = ['tagid' => $tagId, 'next_openid' => $nextOpenId];
  
          return $this->parseJSON('json', [self::API_USERS_OF_TAG, $params]);
      }
docs: Get users from a tag.
  
  @param string $tagId
  @param string $nextOpenId
  
  @return \EasyWeChat\Support\Collection