python list as stack and queue

1def isEmpty(stk): # checks whether the stack is empty or not
2   if stk==[]:
3      return True
4   else:
5      return False
6
7def Push(stk,item): # Allow additions to the stack
8   stk.append(item)
9   top=len(stk)-1
10
11def Pop(stk):
12   if isEmpty(stk): # verifies whether the stack is empty or not
13      print("Underflow")
14   else: # Allow deletions from the stack
15      item=stk.pop()
16      if len(stk)==0:
17         top=None
18      else:
19         top=len(stk)
20         print("Popped item is "+str(item))
21
22def Display(stk):
23   if isEmpty(stk):
24      print("Stack is empty")
25   else:
26      top=len(stk)-1
27      print("Elements in the stack are: ")
28      for i in range(top,-1,-1):
29         print (str(stk[i]))
30
31# executable code
32if __name__ == "__main__":
33   stk=[]
34   top=None
35   Push(stk,1)
36   Push(stk,2)
37   Push(stk,3)
38   Push(stk,4)
39   Pop(stk)
40   Display(stk)

1#Adding elements to queue at the rear end
2def enqueue(data):
3   queue.insert(0,data)
4
5#Removing the front element from the queue
6def dequeue():
7   if len(queue)>0:
8      return queue.pop()
9   return ("Queue Empty!")
10
11#To display the elements of the queue
12def display():
13   print("Elements on queue are:");
14   for i in range(len(queue)):
15      print(queue[i])
16
17# executable code
18if __name__=="__main__":
19   queue=[]
20   enqueue(5)
21   enqueue(6)
22   enqueue(9)
23   enqueue(5)
24   enqueue(3)
25   print("Popped Element is: "+str(dequeue()))
26   display()