docs: def _load_isd_station_metadata(download_path):
      """ Collect metadata for US isd stations.
      """
      from shapely.geometry import Point
  
      # load ISD history which contains metadata
      isd_history = pd.read_csv(
          os.path.join(download_path, "isd-history.csv"),
          dtype=str,
          parse_dates=["BEGIN", "END"],
      )
  
      hasGEO = (
          isd_history.LAT.notnull() & isd_history.LON.notnull() & (isd_history.LAT != 0)
      )
      isUS = (
          ((isd_history.CTRY == "US") & (isd_history.STATE.notnull()))
          # AQ = American Samoa, GQ = Guam, RQ = Peurto Rico, VQ = Virgin Islands
          | (isd_history.CTRY.str[1] == "Q")
      )
      hasUSAF = isd_history.USAF != "999999"
  
      metadata = {}
      for usaf_station, group in isd_history[hasGEO & isUS & hasUSAF].groupby("USAF"):
          # find most recent
          recent = group.loc[group.END.idxmax()]
          wban_stations = list(group.WBAN)
          metadata[usaf_station] = {
              "usaf_id": usaf_station,
              "wban_ids": wban_stations,
              "recent_wban_id": recent.WBAN,
              "name": recent["STATION NAME"],
              "icao_code": recent.ICAO,
              "latitude": recent.LAT if recent.LAT not in ("+00.000",) else None,
              "longitude": recent.LON if recent.LON not in ("+000.000",) else None,
              "point": Point(float(recent.LON), float(recent.LAT)),
              "elevation": recent["ELEV(M)"]
              if not str(float(recent["ELEV(M)"])).startswith("-999")
              else None,
              "state": recent.STATE,
          }
  
      return metadata