What does appending [0] to methods in python do?

Question

What does appending [0] to methods in python do? For example, in the following [0] is appended to a method.

print "Unexpected error:", sys.exc_info()[0]

Answer 1

It calls the method and gets the 0th element from the returned value.

>>> def test():
...   return ['item0', 'item1']
...
>>> test()
['item0', 'item1']
>>> test()[0]
'item0'
>>>