Starting from Python 2.3, the handy enumerate() was introduced.
However, I suggest to add a "reverse" parameter:
>>> lis = ['a', 'b', 'c', 'd']
>>> list(enumerate(lis))
[(0,'a'),(1,'b'),(2,'c'),(3,'d')]
>>> list(enumerate(lis,reverse=True)
[('a',0),('b',1),('c',2),('d',3)]
>>>

A typo in the previous comment:
>>> list(enumerate(lis,reverse=True))
[('a',0),('b',1),('c',2),('d',3)]

What is the use case for this? You seem to want `enumerate` to return (item, index) instead of (index, item) when `reverse=True`? You can achieve this yourself easily a custom generator:

>>> def swapped_enumerate(l):
...   for idx, item in enumerate(l):
...     yield item, idx
...
>>> list(swapped_enumerate(lis))
[('a', 0), ('b', 1), ('c', 2), ('d', 3)]

You can already do this using existing composable tools, including:

>>> list((item, idx) for idx, item in enumerate(lis))
[('a', 0), ('b', 1), ('c', 2), ('d', 3)]
>>>

We won't be adding a parameter to enumerate in order add another way of doing this.

If you really want to pursue this, you should discuss it on the python-ideas mailing list and try to get the idea accepted there. But it really doesn't have any chance of being accepted.