>>> from balls import ballsD_inv


--ini
>>> id_city_D = {
... 77000767: 'Mataró', 88999000: 'Mataró', 99666333: 'Girona',
... 55444333: 'Bcn', 66777888: 'Vic', 
... 10111222: 'Bcn', 22111333: 'Girona',  33121212: 'Bcn',
... }

>>> id_balls_D = { 
... 88999000: ['Lindy Hop'],
... 55444333: ['Rock', 'Lindy Hop'],
... 10111222: ['Lindy Hop', 'Blues', 'Rock'],
... 44555666: ['Lindy Hop', 'Blues', 'Rock'],
... 77000767: ['Lindy Hop', 'Shag'],
... }

>>> solD = ballsD_inv(id_city_D, id_balls_D)

>>> correctD = {
... 'Lindy Hop': [88999000, 55444333, 10111222, 77000767],
... 'Rock': [55444333, 10111222],
... 'Blues': [10111222],
... 'Shag': [77000767]}

--fi

>>> if solD != correctD:
...     print(solD)

>>> solD = ballsD_inv({}, id_balls_D)
>>> correctD = {}
>>> if solD != correctD:
...     print(solD)

>>> solD = ballsD_inv(id_city_D, id_balls_D)

>>> correctD = {
... 'Lindy Hop': [33121212],
... 'Rock': [33121212],
... 'Blues': [33121212],
... 'Shag': [33121212]}

--fi