Exercise:

What is missing?

class Stack:
    def __init__(self):
        self.stack = []
    
    def push(self, element):
        self.stack.append(element)
    
    def pop(self):
        if self.
w3exercise_input_no_0
:
            return "Stack is empty"
        return self.stack.pop()
    
    def peek(self):
        if self.
w3exercise_input_no_1
:
            return "Stack is empty"
        return self.stack[-1]
    
    def isEmpty(self):
        return len(self.stack) == 0
    
    def size(self):
        return len(self.stack)