code: def has(self, url, xpath=None):
          
          if not path.exists(self.db_path):
              return False
  
          return self._query(url, xpath).count() > 0
docs: Check if a URL (and xpath) exists in the cache
  
          If DB has not been initialized yet, returns ``False`` for any URL.
  
          Args:
              url (str): If given, clear specific item only. Otherwise remove the DB file.
              xpath (str): xpath to search (may be ``None``)
  
          Returns:
              bool: ``True`` if URL exists, ``False`` otherwise