您如何确定（编码）堆栈是否为空？

Question

我正在学习数据结构，目前正在堆栈上工作。我想知道您如何确定堆栈是否为空？

from copy import deepcopy

class Stack:

    def __init__(self):
        """
        -------------------------------------------------------
        Initializes an is_empty stack. Data is stored in a Python list.
        Use: s = Stack()
        -------------------------------------------------------
        Returns:
            a new Stack object (Stack)
        -------------------------------------------------------
        """
        self._values = []

    def is_empty(self):
        """
        -------------------------------------------------------
        Determines if the stack is empty.
        Use: b = s.is_empty()
        -------------------------------------------------------
        Returns:
            True if the stack is empty, False otherwise
        -------------------------------------------------------
        """

        # Your code here

Answer 1

如果self._values为空列表，则堆栈为空