>>> from vagons import Vago
>>> v1 = Vago('WX-23', 30, 68)
>>> v1.id
'WX-23'
>>> v1.nseients
30
>>> v1.npeu
68
>>> v1.capacitat()
98
>>> str(v1)
'Vagó WX-23'
>>> v1.id = 'XXXX'
>>> str(v1)
'Vagó XXXX'
>>> v1.npeu = 3
>>> v1.nseients = 7
>>> v1.capacitat()
10