def format_date_for_template(date_start, date_end):
    """
    Formating dates with rules of Russian language for filling Word template
    """
    if date_end != '':
        date_start = f'c {date_start}'
        date_end = f'по {date_end}'
    else:
        date_start = f'на {date_start}'
        date_end = ''
    return date_start, date_end