>>> from pessa import Peça
>>> from validar import peces_valides

--ini-test-peces

>>> l = [Peça('Rei','Groc'), Peça('Peó', 'Negre')]
>>> it = iter(l)
>>> it2 = peces_valides(it)
>>> print(next(it2))
Peó Negre
>>> next(it2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration

--fi-test-peces

>>> l.append(Peça('Cavall', 'Blanca'))
>>> l.append(Peça('Dama', 'Negra'))
>>> l.append(Peça('Elefant', 'Blanc'))
>>> it = iter(l)
>>> it2 = peces_valides(it)
>>> iter(it2) == it2
True
>>> for p in it2:
...     print(str(p))
...
Peó Negre
Dama Negra