>>> x=[1,2,3]
>>> x.index(1)
0
>>> x=[[1,2],[3,4],[5,6]]
>>> x.index([5,6])
2
>>>

>>> map(lambda y: y[0],x).index(5)
2
>>>

index = 0
while not x[0][index] == 5: index += 1

>>> index =0
>>> while not x[index][0] == 5: index += 1
...
>>> index
2