from DoubleLinkedList import DoubleLinkedList

class Stack(DoubleLinkedList):

def __init__(self):

super().__init__()

def push(self,item : object) -> None:

self.add_at_end(item)

def pop(self) -> object:

if not self.is_empty():

return self.delete_from_end()

def is_empty(self) -> bool:

if self.size == 0:

print("Stack is empty")

return True

return False

def print_stack(self) -> None :

self.print_list()

def insert_at_beginning(self,item):

raise NotImplementedError("Insert at Begining is not allowed in Stack.")

def insert(self, pos, item):

raise NotImplementedError("This operation is not allowed in Stack.")

def delete(self, pos):

raise NotImplementedError("This operation is not allowed in Stack.")

def main():

s = Stack()

s.push(3)

s.push(4)

print(s.pop())

print(s.pop())

print(s.pop())

if __name__ == "__main__":

main()