#!/usr/bin/env python3# -*- coding: utf-8 -*-classmates = ['Michael', 'Bob', 'Tracy','123',999, ['asp', 'php']]print(classmates)print(len(classmates))print(classmates[1])print(classmates[-1])classmates.append('Adam')print(classmates[-1])classmates.pop()print(classmates[-1])classmates.pop(1)print(classmates[1])classmates[1] = 'Sarah'print(classmates[1])print(classmates[-1][-1])L = [    ['Apple', 'Google', 'Microsoft'],    ['Java', 'Python', 'Ruby', 'PHP'],    ['Adam', 'Bart', 'Lisa']]print(L[-1][1])print(L[-2][2])print(L[-3][3])