class Class:
global global_decorator
def decorator():
pass
global_decorator = decorator
print(Class.decorator is global_decorator)
# а еще точнее
print(Class.decorator is global_decorator.__get__(None, Class))
# что не всегда означает одно и то же, но для функций это так
Y2xhc3MgQ2xhc3M6CiAgICBnbG9iYWwgZ2xvYmFsX2RlY29yYXRvcgoKICAgIGRlZiBkZWNvcmF0b3IoKToKICAgICAgICBwYXNzCgogICAgZ2xvYmFsX2RlY29yYXRvciA9IGRlY29yYXRvcgoKcHJpbnQoQ2xhc3MuZGVjb3JhdG9yIGlzIGdsb2JhbF9kZWNvcmF0b3IpCiMg0LAg0LXRidC1INGC0L7Rh9C90LXQtQpwcmludChDbGFzcy5kZWNvcmF0b3IgaXMgZ2xvYmFsX2RlY29yYXRvci5fX2dldF9fKE5vbmUsIENsYXNzKSkKIyDRh9GC0L4g0L3QtSDQstGB0LXQs9C00LAg0L7Qt9C90LDRh9Cw0LXRgiDQvtC00L3QviDQuCDRgtC+INC20LUsINC90L4g0LTQu9GPINGE0YPQvdC60YbQuNC5INGN0YLQviDRgtCw0Lo=