可变不可变类型 判断用true和false 成员运算符：in 本栏目推荐文章pythonDay23pythonDay22pythonDay20pythonDay19pythonDay18pythonDay17pythonDay16pythonDay15pythonDay12pythonDay11pythonDay4 pythonDaypythonday4 pythonday4 pythonday pythonday pythonday9 pythonday5 pythonday 22 pythonday7 pythonday 23 pythonday 19 pythonday 17
