>>> from trens import Tren
>>> from vagons import Vago
>>> t1 = Tren('Talgo')
>>> v1 = Vago('WX-23', 30, 68)
>>> t1.afegir_vago(v1)
>>> v2 = Vago('YX-90', 40, 12)
>>> t1.afegir_vago(v2)

>>> t2 = Tren('Alvia')
>>> v3 = Vago('AB-34', 30, 40)
>>> t2.afegir_vago(v3)
>>> v4 = Vago('YX-90', 30, 40)
>>> t2.afegir_vago(v4)
>>> v5 = Vago('YX-90', 30, 40)
>>> t2.afegir_vago(v5)

>>> from usa_tren import mes_capacitat

--ini-mes
>>> t = mes_capacitat(t1, t2)
>>> t.nom
'Alvia'

--fi-mes

>>> v6 = Vago('ZZ-100', 200, 145)
>>> t1.afegir_vago(v6)
>>> t = mes_capacitat(t1, t2)
>>> t.nom
'Talgo'


>>> from usa_tren import seients_tren

--ini-seients

>>> seients_tren(t1)
270
>>> seients_tren(t2)
90

--fi-seients

>>> from usa_tren import vagons_capacitat

--ini-capacitat

>>> it = vagons_capacitat(t1, 70)
>>> for v in it:
...   print(v, v.nseients, v.npeu)
Vagó WX-23 30 68
Vagó ZZ-100 200 145

>>> next(it, 'final')
'final'

--fi-capacitat