def date_to_filename(base_path, raw_date_string):
    """
    given some date like MONTH/DAY/YEAR, make a filename like base_path/YEAR/MONTH/DAY.md
    """
    raw_date_string = raw_date_string[:-1]
    month, day, year = raw_date_string.split("/")
    relative_path = "{}/{}/{}.md".format(year, month, day)
    return base_path / relative_path