Reverse a linked list:

"""
 Reverse a linked list
 head could be None as well for empty list
 Node is defined as

 class Node(object):

   def __init__(self, data=None, next_node=None):
       self.data = data
       self.next = next_node

 return back the head of the linked list in the below method.
"""

def Reverse(head):
    prev = None
    current = head
    while current!=None:
        temp = current.next
        current.next = prev
        prev = current
        current = temp
    return prev