python decorators, nested function

Why second sample does not works?

Because you are calling the function on the return, you are not returning a function.

Why args,kwargs are "magically" appears if we are using a nested function?

They don't appear magically, we are declaring them, as in:

def deco(*args, **kwargs):

These are generic, and will match any function signature (argument list). You don't have to call them args and kwargs , that's just a convention, you could call them sharon and tracy .

What can i do, to make 2nd sample work? Except nesting another function, ofcourse.

Well you don't say what you expect the 2nd sample to do. But I guess to turn it into a decorator then:

def func(f):
    return f

But that's not doing a lot!