code: def _format_dataframe(
          df: pd.DataFrame, nautical_units=True
      ) -> pd.DataFrame:
          if "callsign" in df.columns and df.callsign.dtype == object:
              df.callsign = df.callsign.str.strip()
          if nautical_units:
              df.altitude = df.altitude / 0.3048
              if "geoaltitude" in df.columns:
                  df.geoaltitude = df.geoaltitude / 0.3048
              if "groundspeed" in df.columns:
                  df.groundspeed = df.groundspeed / 1852 * 3600
              if "vertical_rate" in df.columns:
                  df.vertical_rate = df.vertical_rate / 0.3048 * 60
          df.timestamp = pd.to_datetime(df.timestamp * 1e9).dt.tz_localize("utc")
          if "last_position" in df.columns:
              df = df.query("last_position == last_position").assign(
                  last_position=pd.to_datetime(
                      df.last_position * 1e9
                  ).dt.tz_localize("utc")
              )
          return df.sort_values("timestamp")