Getting currency for current day.

    see example: http://www.cbr.ru/scripts/Root.asp?PrtId=SXML

    :param date_req:
    :type date_req: datetime.datetime
    :param lang: language of API response ('eng' || 'rus')
    :type lang: str

    :return: :class: `Element <Element 'ValCurs'>` object
    :rtype: ElementTree.Element

def get_daily_rates(date_req: datetime.datetime = None, lang: str = 'rus') -> Element:
    """ Getting currency for current day.

    see example: http://www.cbr.ru/scripts/Root.asp?PrtId=SXML

    :param date_req:
    :type date_req: datetime.datetime
    :param lang: language of API response ('eng' || 'rus')
    :type lang: str

    :return: :class: `Element <Element 'ValCurs'>` object
    :rtype: ElementTree.Element
    """
    if lang not in ['rus', 'eng']:
        raise ValueError('"lang" must be string. "rus" or "eng"')

    base_url = const.CBRF_API_URLS['daily_rus'] if lang == 'rus' \
        else const.CBRF_API_URLS['daily_eng']

    url = base_url + 'date_req=' + utils.date_to_str(date_req) if date_req else base_url

    response = requests.get(url=url)

    return XML(response.text)