Python Data Structures and Algorithms

A doubly linked list node

The Python code that creates a class to capture what a doubly linked list node is includes in its initializing method, the prev, next, and data instance variables. When a node is newly created, all these variables default to None:

    class Node(object):         def __init__(self, data=None, next=None, prev=None):            self.data = data            self.next = next            self.prev = prev 

The prev variable holds a reference to the previous node, while the next variable continues to hold a reference to the next node.