>>> spam = ['dog', 'cat', 'bat', 'mouse']
>>> spam
['dog', 'cat', 'bat', 'mouse']
>>> for i in range(len(spam)): print(i, spam[i])
...
0 dog
1 cat
2 bat
3 mouse
>>> for index, value in enumerate(spam): print(index, value)
...
0 dog
1 cat
2 bat
3 mouse
>>>