>>> import networkx as nx
>>> from engranatges import moviment

>>> g = nx.Graph()
>>> g.add_edges_from([('A', 'C'), ('E', 'F'), ('J', 'K'), 
...                   ('D', 'I'), ('I', 'H'), ('H', 'G')], unio='DENT')
>>> g.add_edges_from([('B', 'C'), ('C', 'D'), ('F', 'I')], unio='POL') 

--inici--

>>> moviment(g, 'B') == {'C', 'F', 'H', 'E', 'G', 'I', 'D', 'A'}
True
>>> moviment(g, 'J') == {'K'}
True

--fi--

>>> g.add_node('M')
>>> moviment(g, 'M') == set()
True

>>> g.add_edge('M', 'J', unio='POL')
>>> moviment(g, 'K') == {'J', 'M'}
True