def get_users_preferred_timezone(user, service):
    """
    Determines the users preferred timezone by checking what timezone they use for their primary google calendar

    :param user: Django User object for the user whose calendar is being accessed
    :return: A string representation of the timezone:

        - "Etc/GMT+8"
    """
    primary_calendar = service.calendarList().get(calendarId='primary').execute()

    return primary_calendar['timeZone']