def filter_value(entry, values=None):
    """
    Returns True if it should be filtered.
    Only take calls with filter values in the list provided
    if None provided, assume that filter_value must be PASS or blank '.'
    """
    if values is None:
        return len(entry.filter) != 0 and 'PASS' not in entry.filter
    return values.intersection(entry.filter)