class Stack:
def __init__(self):
self.list = LinkedList()
# Get the size of the stack
def size(self) -> int:
return self.list.size()
# Check if the stack is empty
def isEmpty(self) -> bool:
return self.size() == 0
# Get the value of an item from the top of a stack
def peek(self) -> object:
if (self.isEmpty()):
raise Exception('Cannot perform peek on an empty list')
return self.list.peekLast()
# Remove an item from the top of a stack
def pop(self) -> LinkedList.Node:
if (self.isEmpty()):
raise Exception('Cannot perform poll on an empty list')
return self.list.removeLast()
# Add item to the back of the stack
def push(self, item: object):
if item is None: return Exception('Cannot add a None object')
self.list.addLast(item)
