>>> import networkx as nx
>>> from crea_metro_bcn import crea_xarxa_metro
>>> g = crea_xarxa_metro()

--ini-enunciat

>>> from mes_metro import quines_linies
>>> quines_linies(g, 'Lesseps', 'Drassanes')
['L3']
>>> quines_linies(g, 'Girona', 'Hostafrancs')
[]
>>> quines_linies(g, 'Diagonal', 'Sants Estacio')
['L3', 'L5']

--fi-enunciat

>>> quines_linies(g, 'Catalunya', 'Clot')
['L1']
>>> quines_linies(g, 'La Sagrera', 'Bon Pastor')
['L9']