>>> from cercadic import index_llista
>>> l1 = [2, 5, 7, 15, 19, 23, 25, 28, 31, 33, 36, 37, 42, 45, 48]
>>> index_llista(l1, 28)
7
>>> index_llista(l1, 1)
-1
>>> index_llista(l1, 7)
2
>>> index_llista(l1, 37)
11
>>> index_llista(l1, 2)
0
>>> index_llista(l1, 48)
14
>>> index_llista(l1, 6)
-1
>>> index_llista(l1, 27)
-1
>>> index_llista(l1, 35)
-1
>>> index_llista(l1, 50)
-1

>>> l2 = [3, 6, 7, 12, 15, 21, 24, 27, 33, 37, 38, 39, 41, 47]
>>> index_llista(l2, 27)
7
>>> index_llista(l2, 12)
3
>>> index_llista(l2, 3)
0
>>> index_llista(l2, 47)
13
>>> index_llista(l2, 39)
11
>>> index_llista(l2, 1)
-1
>>> index_llista(l2, 55)
-1
>>> index_llista(l2, 5)
-1
>>> index_llista(l2, 25)
-1
>>> index_llista(l2, 35)
-1