Class Stack

class Stack:
     def __init__(self):
          self.items = []

     def isEmpty(self):
          return self.items == []

     def push(self, item):
          self.items.append(item)

     def rpush(self, item):
          self.items.append(item)
          return self

     def pop(self):
          return self.items.pop()

     def penultimate_element(self):
          return self.items[len(self.items) - 1]

     def size(self):
          return len(self.items)

     def __str__(self):
          return str(self.items)

     def __add__(self, other):
          if type(other) is int or type(other) is float:
               return self.rpush(other)
          elif type(other) is type(self):
               for i in range(len(other.items)):
                    self.push(other.items[i])
               return self
          else:
               return 'ERROR'

     def clearall(self):
          self.items.clear()


stack1 = Stack()
stack2 = Stack()

if stack1.isEmpty():
     print('Empty')

stack1.push(1)
stack1.push(2)
stack1.push(3)
stack1.push(4)
stack2.push(2)
stack2.push(2)
stack2.push(2)
stack2.push(2)

print(stack1.penultimate_element())

print(stack1)
print(stack2)

result = stack1 + stack2
print(result)
print(type(result))
result.clearall()
print(result)