Queue_using_LL.py

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

class Queue:
 def __init__(self):
 self.head = None
 self.last = None

 def enqueue(self, data):
 if not self.last:
 self.head = Node(data)
 self.last = self.head
 else:
 self.last.next = Node(data)
 self.last = self.last.next

 def dequeue(self):
 if not self.head:
 return None
 val = self.head.data
 self.head = self.head.next
 return val

 def display(self):
 temp = self.head
 while temp != None:
 print(temp.data)
 temp = temp.next

x = Queue() # Creating object of queue class
x.enqueue(1) # Add 1 to the queue
x.enqueue(2)# Add 2 to the queue
x.display() # 1 => 2
print(x.dequeue()) # Deleting the first element of the queue.
x.display() # 2
print(x.dequeue()) # 2
print(x.dequeue()) # None(because queue is already empty)