How can I reverse a list in python?

This syntax works for any interable, not just lists. It just returns a new reversed list, but it doesn't modify the original one.

L=[0, 10, 20, 40]
L[::-1]
[40, 20, 10, 0]

The syntax represanted as [start:stop:step], so step is -1. You're only returning the values in reverse 

To actually reverse the list,

L=L[::-1] 


Ref:
https://docs.python.org/release/2.3.5/whatsnew/section-slices.html

http://stackoverflow.com/questions/3940128/how-can-i-reverse-a-list-in-python