def make_list(value):
    """Return a list of items from a comma-separated string.

    Surrounding whitespace will be stripped from the list items. If the
    provided string is empty, an empty list will be returned. This function
    will also accept the value None and return an empty list.
    """
    if value is None:
        return []
    return list(filter(None, [s.strip() for s in value.split(',')]))