Search an element in doubly linked list in python

Python program for Search an element in doubly linked list. Here problem description and other solutions.

#  Python 3 program for
#  Find node in doubly linked list

#  This is Linked List Node
class LinkNode :
	def __init__(self, data) :
		self.data = data
		self.next = None
		self.prev = None
	

class DoublyLinkedList :
	def __init__(self) :
		self.head = None
		self.tail = None
	
	#  Insert new node at end position
	def insert(self, value) :
		#  Create a node
		node = LinkNode(value)
		if (self.head == None) :
			#  Add first node
			self.head = node
			self.tail = node
			return
		
		#  Add node at last position
		self.tail.next = node
		node.prev = self.tail
		self.tail = node
	
	#  Display node element of doubly linked list
	def display(self) :
		if (self.head == None) :
			print("Empty Linked List")
		else :
			print("Linked List Head to Tail :", end = "")
			#  Get first node of linked list
			temp = self.head
			#  iterate linked list 
			while (temp != None) :
				#  Display node value
				print(" ", temp.data, end = " ")
				#  Visit to next node
				temp = temp.next
			
			print("\nLinked List Tail to Head :", end = "")
			#  Get last node of linked list
			temp = self.tail
			#  iterate linked list 
			while (temp != None) :
				#  Display node value
				print(" ", temp.data, end = " ")
				#  Visit to prev node
				temp = temp.prev
			
		
	
	def searchKey(self, key) :
		#  Get first node
		front = self.head
		#  Get last node
		rear = self.tail
		while (front != None and rear != None) :
			if (front.data == key or rear.data == key) :
				#  When node key exists
				return True
			
			if (front == rear or front.next == rear) :
				#  When get middle nodes
				return False
			
			#  Visit to right node
			front = front.next
			#  Visit to left node
			rear = rear.prev
		
		#  Empty Linked List
		return False
	

def main() :
	dll = DoublyLinkedList()
	#  Insert following linked list nodes
	dll.insert(8)
	dll.insert(2)
	dll.insert(23)
	dll.insert(-4)
	dll.insert(7)
	dll.insert(3)
	dll.insert(9)
	#  Display all node
	dll.display()
	key = -4
	#  Test A
	if (dll.searchKey(key)) :
		print("\nNode key ", key ," are exist")
	else :
		print("\nNode key ", key ," are not exist")
	
	#  Test B
	key = 11
	if (dll.searchKey(key)) :
		print("Node key ", key ," are exist")
	else :
		print("Node key ", key ," are not exist")
	
	#  Test C
	key = 3
	if (dll.searchKey(key)) :
		print("Node key ", key ," are exist")
	else :
		print("Node key ", key ," are not exist")
	

if __name__ == "__main__": main()

Output

Linked List Head to Tail :  8   2   23   -4   7   3   9
Linked List Tail to Head :  9   3   7   -4   23   2   8
Node key  -4  are exist
Node key  11  are not exist
Node key  3  are exist