def as_utc_with_z(date):
    date_str = date.astimezone(tz.UTC).isoformat()
    return f"{date_str[:-6]}Z"

def parse_datetime(dt):
    d = dateutil.parser.parse(dt)
    if d.tzinfo is None:
        d = d.replace(tzinfo=tz.tzlocal())

    return d

def main():
    parser = argparse.ArgumentParser()
    ...
    args = parser.parse_args(argv)

    fetch_range = (parse_datetime(args.begin), parse_datetime(args.end))
    ...
    fetch_range = [as_utc_with_z(x) for x in fetch_range]

    kwargs = { 
         "host": credentials["host"],
         "port": credentials["port"],
         "username": credentials["user"],
         "password": credentials["password"],
         "database": credentials["db"],
         "ssl": True,
         "verify_ssl": True,
    }   

    client = InfluxDBClient(**kwargs)

    query = f"SELECT * FROM verzuolo WHERE time >= '{fetch_range[0]}' AND time <= '{fetch_range[1]}'"
    res = client.query(query)
    ...