Els exemples que compten per la nota són només els que van seguits de
``# doctesttag: +TAG=...``

>>> from itertools import *

Tests exercici 1
----------------

>>> from capgira import swap
>>> lc1 = range(10)
>>> lc2 = range(9)
>>> lc3 = 'ABCDEFGHIJ'
>>> lc4 = [(x,x**2) for x in range(10)]
>>> lc5 = count(3,2)

>>> for elem in swap(iter(lc1)):	# doctesttag: +TAG=1_capgira
...    print(elem, end=',')    
1,0,3,2,5,4,7,6,9,8,
>>> for elem in swap(iter(lc2)):	# doctesttag: +TAG=1_capgira
...    print(elem, end=',')  
1,0,3,2,5,4,7,6,8,
>>> for elem in swap(iter(lc3)):	# doctesttag: +TAG=1_capgira
...    print(elem, end=',')   
B,A,D,C,F,E,H,G,J,I,
>>> for elem in swap(iter(lc4)):	# doctesttag: +TAG=1_capgira
...    print(elem, end=',')   
(1, 1),(0, 0),(3, 9),(2, 4),(5, 25),(4, 16),(7, 49),(6, 36),(9, 81),(8, 64),
>>> for elem in islice(swap(lc5), 10, 30, 1):	# doctesttag: +TAG=1_capgira
...    print(elem, end=',')
25,23,29,27,33,31,37,35,41,39,45,43,49,47,53,51,57,55,61,59,

Tests exercici 2
----------------

>>> from countdown import comptar_enrere
>>> for elem in comptar_enrere(iter([3, 5, 2, 8])):  # doctesttag: +TAG=2_countdown
...    print(elem, end=',')
3,2,1,5,4,3,2,1,2,1,8,7,6,5,4,3,2,1,
>>> itr = comptar_enrere(iter([1, 10, 2, 8, 1]))  
>>> for x in itr:  # doctesttag: +TAG=2_countdown
...    print(x, end=',')
1,10,9,8,7,6,5,4,3,2,1,2,1,8,7,6,5,4,3,2,1,1,
>>> itr = comptar_enrere(iter([4,3,4]))  
>>> for x in itr: # doctesttag: +TAG=2_countdown
...    print(x, end=',')
4,3,2,1,3,2,1,4,3,2,1,