code: def check_download(self, link_item_dict: Dict[str, LinkItem], folder: Path, log: bool = True) -> Tuple[
          Dict[str, LinkItem], Dict[str, LinkItem]]:
          
          succeed = {link: item for link, item in link_item_dict.items() if folder.joinpath(item.name).is_file()}
          lost = {link: item for link, item in link_item_dict.items() if link not in succeed}
  
          if lost and log:
              for link, item in lost.items():
                  self.log.error(f"Not downloaded: {self.info.host+link} - {item.name}")
  
          return succeed, lost
docs: Check if the download of the given dict was successful. No proving if the content of the file is correct too.
  
          :param link_item_dict: dict which to check
          :type link_item_dict: Dict[str, ~unidown.plugin.link_item.LinkItem]
          :param folder: folder where the downloads are saved
          :type folder: ~pathlib.Path
          :param log: if the lost items should be logged
          :type log: bool
          :return: succeeded and lost dicts
          :rtype: Tuple[Dict[str, ~unidown.plugin.link_item.LinkItem], Dict[str, ~unidown.plugin.link_item.LinkItem]]