1，isinstance和issubclass

　　isinstance(obj,cls)检查是否obj是否是类 cls 的对象

class Foo(object):
     pass
  
obj = Foo()
  
isinstance(obj, Foo)

　　issubclass(sub, super)检查sub类是否是 super 类的派生类 

class Foo(object):
    pass
 
class Bar(Foo):
    pass
 
issubclass(Bar, Foo)