How does iteration of any enumerate object work in python?

Question

I have a list in python ([1,2,3]). I enumerate it using enumerate(l), where l is a list object. I can iterate the enumerate object only once -

for item in e:
    print i

This loop prints the enumerate object elements. But when I again loop through it, it prints nothing. What is happening in the background? Why does enumerate object does not print its elements on second iteration?