7. Write a Python program to implement a stack using list.

 class Stack:

def __init__(self):

self.items = []

 

defis_empty(self):

returnself.items == []

 

def push(self, item):

self.items.append(item)

 

def pop(self):

if not self.is_empty():

returnself.items.pop()

else:

return None

 

def peek(self):

if not self.is_empty():

returnself.items[-1]

else:

return None

 

def size(self):

returnlen(self.items)

 

if __name__ == "__main__":

stack = Stack()

stack.push(1)

stack.push(2)

stack.push(3)

print("Popped:", stack.pop())

print("Peek:", stack.peek())

print("Size:", stack.size())