>>> from bikes import bikeD_gen

>>> id_city_D = {
... 667: 'Mu', 554: 'Mu', 
... 889: 'Milano', 101: 'Milano', 334: 'Milano',
... 445: 'Barcelona', 221: 'Manchester'
... }

>>> id_bike_D = {
... 667: 'Du', 778: 'Du', 889: 'Du', 
... 101:'KTM', 554: 'Du', 221: 'Du'}    
>>> solD = bikeD_gen(id_city_D, id_bike_D)
>>> correctD = {
... 'Du': [221, 554, 667, 889],
... 'KTM': [101],
... }
>>> for k in solD:
...     solD[k].sort()
>>> if solD != correctD:        # doctesttag: +TAG=1_bikeD_gen
...     print(solD)

>>> bikeD_gen(id_city_D, {})    # doctesttag: +TAG=1_bikeD_gen
{}

>>> bikeD_gen({}, id_bike_D)    # doctesttag: +TAG=1_bikeD_gen
{}

>>> id_bike_D = {667: 'Du', 889: 'Du', 101:'Du'}
>>> solD = bikeD_gen(id_city_D, id_bike_D)
>>> for k in solD:
...     solD[k].sort()
>>> if solD != {                # doctesttag: +TAG=1_bikeD_gen
... 'Du':[101, 667, 889],
... }:
...     print(solD)

>>> id_bike_D = {
... 667: 'Du', 778: 'Du', 889: 'Du', 
... 101: 'KTM', 334: 'HONDA', 554: 'HONDA',
... 99111000: 'Triumph', 445: 'Triumph',  221: 'Du',
... }
>>> solD = bikeD_gen(id_city_D, id_bike_D)
>>> for k in solD:
...     solD[k].sort()
>>> if solD != {                # doctesttag: +TAG=1_bikeD_gen
... 'Du': [221, 667, 889],
... 'KTM': [101],
... 'HONDA': [334, 554],
... 'Triumph': [445], 
... }:
...     print(solD)

>>> from bikes import cityD_gen

>>> id_city_D = {
... 667: 'Mu', '55444333D': 'Mu', 
... 889: 'Milano', 101: 'Milano', 334: 'Milano',
... 44555666: 'Bcn', '22111333L': 'Manchester'
... }

>>> id_bikes_D = {
... 889: ['Du'], 
... 778: ['Du', 'Triumph'], 
... 334: ['Du'],
... 667: ['Du', 'BMW'], 
... 44555666: ['KTM'],
... 101: ['Du','KTM'],
... }

>>> solD = cityD_gen(id_city_D, id_bikes_D, 'Du') 
>>> correctD = {
... 'Milano': [101, 334, 889], 
... 'Mu': [667], 
... 'Unknown': [778],
... }
>>> if solD != correctD:        # doctesttag: +TAG=2_cityD_gen
...     print(solD)

>>> solD = cityD_gen({}, id_bikes_D, 'Du')
>>> correctD = {'Unknown': [101, 334, 667, 778, 889]}
>>> if solD != correctD:        # doctesttag: +TAG=2_cityD_gen
...     print(solD)


>>> solD = cityD_gen(id_city_D, id_bikes_D, 'KTM')
>>> correctD = {'Milano':[101], 'Bcn': [44555666]}
>>> if solD != correctD:        # doctesttag: +TAG=2_cityD_gen
...     print(solD)

>>> cityD_gen(id_city_D, {}, 'Triumph')    # doctesttag: +TAG=2_cityD_gen
{}