def get_year_month_day(node):
    """
    Retorna os valores respectivos dos elementos "year", "month", "day".

    Parameters
    ----------
    node : lxml.etree.Element
        Elemento do tipo _date_, que tem os elementos "year", "month", "day".

    Returns
    -------
    tuple of strings
        ("YYYY", "MM", "DD")
    None se node is None

    """
    if node is not None:
        return tuple(
            [(node.findtext(item) or "").zfill(2)
             for item in ["year", "month", "day"]]
        )