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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def setup_timezone(timezone: str) -> None: """Shortcut helper to configure timezone for backend application. :param timezone: Timezone to use, e.g. "UTC", "Europe/Kiev". """

    if timezone and hasattr(time, 'tzset'):
        tz_root = '/usr/share/zoneinfo'
        tz_filename = os.path.join(tz_root, *(timezone.split('/')))

        if os.path.exists(tz_root) and not os.path.exists(tz_filename):
            raise ValueError('Incorrect timezone value: {0}'.format(timezone))

        os.environ['TZ'] = timezone
        time.tzset()