# A simple Python program to introduce a linked list
 
# Node class
class Node:
 
    # Function to initialise the node object
    def __init__(self, data):
        self.data = data  # Assign data
        self.next = None  # Initialize next as null
 
 
# Linked List class contains a Node object
class LinkedList:
 
    # Function to initialize head
    def __init__(self):
        self.head = None
 
 
# Code execution starts here
if __name__=='__main__':
 
    # Start with the empty list
    llist = LinkedList()
 
    llist.head = Node(1)
    second = Node(2)
    third = Node(3)
 
    '''
    Three nodes have been created.
    We have references to these three blocks as head,
    second and third
 
    llist.head        second              third
         |                |                  |
         |                |                  |
    +----+------+     +----+------+     +----+------+
    | 1  | None |     | 2  | None |     |  3 | None |
    +----+------+     +----+------+     +----+------+
    '''
 
    llist.head.next = second; # Link first node with second
 
    '''
    Now next of first Node refers to second.  So they
    both are linked.
 
    llist.head        second              third
         |                |                  |
         |                |                  |
    +----+------+     +----+------+     +----+------+
    | 1  |  o-------->| 2  | null |     |  3 | null |
    +----+------+     +----+------+     +----+------+
    '''
 
    second.next = third; # Link second node with the third node
 
    '''
    Now next of second Node refers to third.  So all three
    nodes are linked.
 
    llist.head        second              third
         |                |                  |
         |                |                  |
    +----+------+     +----+------+     +----+------+
    | 1  |  o-------->| 2  |  o-------->|  3 | null |
    +----+------+     +----+------+     +----+------+
    '''