implement 2 stacks python using array

class ArrayStack:
	def __init__(self):
		self._data = []

	def __len(self):
		return len(self._data)

	def is_empty(self):
		return len(self._data) == 0

	def push(self, e):
		self._data.append(e)

	def pop(self):
		if self.is_empty():
			raise Empty('stack is empty')
		else:
			return self._data.pop()

	def top(self):
		if self.is_empty():
			raise Empty('Stack is empty')
		else:
			return self._data[-1]

	@property
	def data(self):
		return self._data


class Empty(Exception):
	pass

# Python Script to Implement two stacks in a list 
class twoStacks: 
      
    def __init__(self, n):     # constructor 
        self.size = n 
        self.arr = [None] * n 
        self.top1 = -1
        self.top2 = self.size 
          
    # Method to push an element x to stack1 
    def push1(self, x): 
          
        # There is at least one empty space for new element 
        if self.top1 < self.top2 - 1 : 
            self.top1 = self.top1 + 1
            self.arr[self.top1] = x 
  
        else: 
            print("Stack Overflow ") 
            exit(1) 
  
    # Method to push an element x to stack2 
    def push2(self, x): 
  
        # There is at least one empty space for new element 
        if self.top1 < self.top2 - 1: 
            self.top2 = self.top2 - 1
            self.arr[self.top2] = x 
  
        else : 
           print("Stack Overflow ") 
           exit(1) 
  
    # Method to pop an element from first stack 
    def pop1(self): 
        if self.top1 >= 0: 
            x = self.arr[self.top1] 
            self.top1 = self.top1 -1
            return x 
        else: 
            print("Stack Underflow ") 
            exit(1) 
  
    # Method to pop an element from second stack 
    def pop2(self): 
        if self.top2 < self.size: 
            x = self.arr[self.top2] 
            self.top2 = self.top2 + 1
            return x 
        else: 
            print("Stack Underflow ") 
            exit() 
  
# Driver program to test twoStacks class 
ts = twoStacks(5) 
ts.push1(5) 
ts.push2(10) 
ts.push2(15) 
ts.push1(11) 
ts.push2(7) 
  
print("Popped element from stack1 is " + str(ts.pop1())) 
ts.push2(40) 
print("Popped element from stack2 is " + str(ts.pop2())) 
  
# This code is contributed by Sunny Karira