Implement the data structure DoublyLinkedList with the following characteristics:

- DoublyLinkedList() creates a new doubly linked list that is empty. It needs no parameters and returns nothing. Assume the items in the list are unique

-addFirst(item) adds a new Node with value=item at the beginning of the list. It needs the item and returns nothing.

-addLast(item) adds a new Node with value=item at the end of the list. It needs the item and returns nothing.

-addBefore(pnode_value, item) adds a new Node with value=item before the Node with value=pnode_value. It needs the value of the reference Node and the item to be added, returns nothing. You can assume the reference node is in the list.

-addAfter(pnode_value, item) adds a new Node with value=item after the Node with value=pnode_value. It needs the value of the reference Node and the item to be added, returns nothing. You can assume the reference node is in the list.

Here is the code:

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

def getValue(self): return self.value

def getNext(self): return self.next

def setValue(self,new_value): self.value = new_value

def setNext(self,new_next): self.next = new_next

def getPrevious(self): return self.prev

def setPrevious(self,new_prev): self.prev = new_prev

def __str__(self): return ("{}".format(self.value))

__repr__ = __str__

class DoublyLinkedList: # Do NOT modify the constructor def __init__(self): self.head = None def addFirst(self, value): node = Node(value) node.next = self.head if self.head is not None: self.head.prev = node self.head = node def addLast(self, value): # write your code here def addBefore(self, pnode_value, value): # write your code here def addAfter(self, pnode_value, value): # write your code here

def printDLL(self): temp=self.head print(" Traversal Head to Tail") while temp: print(temp.getValue(), end=' ') last = temp temp=temp.getNext() print(" Traversal Tail to Head") while(last is not None): print(last.getValue(), end=' ') last = last.prev

def getNode(self,value): current=self.head found=False while current!=None and not found: if current.getValue()==value: found=True return current else: current=current.getNext() return