How to define the [push] method in a linked list to implement a stack?

I got this error and tried to fix it dozen times. still won't work......

F# 5. (10 points) Programming Exercise 22 from Chapter 4 of your textbook. Use the class and # method names given in Chapter 4.4 in your digital textbook Eclass sNode: def __init__(self,data): self.data = data self.next = None Fclass stack: def init__(self): self.base = None defmisEmpty(self) return self.base == None def push(self, data): current = self.base temp = sNode (data) while current != None and current.next != None: current = current.next current.next = temp def pop (self): if self.base == None: return print('Empty List!') temp = self.base self.base = self.base.next C:\Users\15306\PycharmProjects\pythonProject3\venv\Scripts\python.exe C:\Users\15306\PycharmProje Traceback (most recent call last): File "C:\Users\15306\PycharmProjects\pythonProject3\HW2.py", line 218, in x.push(1) File "C:\Users\15306\PycharmProjects\python Project3\HW2.py", line 185, in push current.next = temp AttributeError: 'NoneType' object has no attribute 'next