(seats)
Find and return seat numbers that are unassigned.

    :param seats: dict - seating chart.
    :return: list - list of seat numbers available for reserving..
Find and return seat numbers that are unassigned.
Find and return seat numbers that are unassigned .
def find_all_available_seats(seats):
    """Find and return seat numbers that are unassigned.

    :param seats: dict - seating chart.
    :return: list - list of seat numbers available for reserving..
    """

    pass
def find_all_available_seats ( seats ) : pass