users = ["alex",0,True,[11,22,33,"老男孩"],[1,['alex','oldboy'],2,3]]
users[0] users[2] users[0][2] users[3] # [11,22,33,"老男孩"] users[3][-1] # "老男孩" users[3][-1][1] # '男' users[3] = 666
