def make_date(year, month, day):
    """
    Make from three parametres year, month, day, date_string in format: "Year-Month_Day". Also, if day or month < 10, added 0 before it.
    """
    new_year = str(year)
    if day < 10:
        new_day = '0' + str(day)
    else:
        new_day = str(day)
    if month < 10:
        new_month = '0' + str(month)
    else:
        new_month = str(month)
    string = new_year + '-' + new_month + '-' + new_day
    return string
