code: def id_for(self, city_name):
          
          line = self._lookup_line_by_city_name(city_name)
          return int(line.split(",")[1]) if line is not None else None
docs: Returns the long ID corresponding to the first city found that matches
          the provided city name. The lookup is case insensitive.
  
          .. deprecated:: 3.0.0
             Use :func:`ids_for` instead.
  
          :param city_name: the city name whose ID is looked up
          :type city_name: str
          :returns: a long or ``None`` if the lookup fails