Can you give an example of a data structure representing a stack?

A stack is a data structure with the Last In, First Out (LIFO) principle, where the last added element is retrieved first.

In Python, a stack can be implemented using a list, with the append() method for adding elements and pop() for removing them:

stack = []  # empty stack

# Adding elements
stack.append(1)
stack.append(2)
stack.append(3)

print(stack)  # [1, 2, 3]

# Removing elements
top = stack.pop()
print(top)    # 3
print(stack)  # [1, 2]

You can also use collections.deque for more efficient addition and removal operations from both ends, but a list is perfectly suitable for a stack.