Stack data structure in python

Question

I have 2 issues with the code below:

1. push(o) throws an exception TypeError: can only assign an iterable.

2. Should I throw an exception if pop()

Answer 1

class Stack:
    def __init__(self):
        self.stack = []
    def pop(self):
        if self.is_empty():
            return None
        else:
            return self.stack.pop()
    def push(self, d):
        return self.stack.append(d)
    def peek(self):
        if self.is_empty():
            return None
        else:
            return self.stack[-1]
    def size(self):
        return len(self.stack)
    def is_empty(self):
        return self.size() == 0