练习7

#使用__class__和__base__属性来查看继承层次def classtree(cls,indent):    print('.'*indent+cls.__name__)    for supercls in cls.__bases__:        classtree(supercls,indent+3)def instancetree(inst):    print('tree of %s'% inst)    classtree(inst.__class__,3)def test():    class a:pass    class b(a):pass    class c(a):pass    class d(b,c):pass    class e:pass    class f(d,e):pass    instancetree(b())    instancetree(f())test()