Function to read csv data downloaded from Blitzorgs historical data
        section. Time is in POSIX timestamps (x1000000000). An eg is kept in
        stormstats/egdata/archive_2_raw.txt. If no data file is specified
        the function will assume you want to read this example data. Geopandas
        dataframe will be returned.

        :paramter f: optional string giving path/filename of csv data

        :Example:

        >>> stormstats.storm.read_blitzorg_csv(f=None)

def read_blitzorg_csv(f=None):
        """
        Function to read csv data downloaded from Blitzorgs historical data
        section. Time is in POSIX timestamps (x1000000000). An eg is kept in
        stormstats/egdata/archive_2_raw.txt. If no data file is specified
        the function will assume you want to read this example data. Geopandas
        dataframe will be returned.

        :paramter f: optional string giving path/filename of csv data

        :Example:

        >>> stormstats.storm.read_blitzorg_csv(f=None)
        """
        factor = 1000000000  # don't change this magic number! Its from Bzorg.
        if f:
            tmp = pd.read_csv(f)
        else:
            f = pkg.resource_filename('stormstats', "egdata/archive_2_raw.txt")
            tmp = pd.read_csv(f)
        dt_list = [dt.datetime.fromtimestamp(ts/factor).strftime(
            '%Y-%m-%d %H:%M:%S:%f') for ts in tmp.time]
        tmp_list = [[Point(lon, lat), ts] for lon, lat, ts in
                    zip(tmp.lon, tmp.lat, dt_list)]
        df = gpd.GeoDataFrame(tmp_list, columns=['geometry', 'dt'])
        return df