QueueLL.py

class Node:
    def __init__(self,data):
        self.data=data
        self.next=None
        
class QueueLinkedList:
    
    def __init__(self):
       self.front=None
       self.rear=None
  
    def is_empty(self):
        return self.front is None

    def enqueue(self,item):
        new_node = Node(item)
        if self.is_empty():
            self.front=new_node
            self.rear=new_node
        else:
            self.rear.next=new_node
            self.rear=new_node
            
    def dequeue(self):
        if not self.is_empty():
            dequeued_item=self.front.data
            self.front=self.front.next
            if self.front is None:
                self.rear=None
            return dequeued_item
        else:
            raise IndexError("dequeued from an empty queue")
            
    def peek(self):
        if not self.is_empty():
            return self.front.data
        else:
            raise IndexError("peek from an empty queue")
            
    def size(self):
        count=0
        current=self.front
        while current:
            count+=1
            current=current.next
        return count
        
queue=QueueLinkedList()
queue.enqueue(1)
queue.enqueue(2)
queue.enqueue(3)
print("Front of the queue:",queue.peek())
print("dequeue:",queue.dequeue())