from datetime import datetime


def generate_folder(source_date):

    """
    Generate partial folder name based on provided source_date
    :param source_date: datetime
    """

    assert isinstance(source_date, datetime)

    date_part = source_date.date()

    year = date_part.year
    month = date_part.month
    day = date_part.day

    path = "{0:04d}/{1:02d}-{2:02d}".format(year, month, day)

    return path