how to add a member variable to a python object

Question

class Empty:
    pass

a = Empty()
a.m = 1

the above code works well and there is no error.

a = object()
a.m = 1 # it throws AttributeError

but this code throws an exception.

AttributeError: 'object' object has no attribute 'm'

What is the difference?

I just want an empty object and add some variable to it.

How can I do that? Should I make an empty class?