class_or_instance.py

import functools
 
class class_or_instance(object):
    def __init__(self, fn):
        self.fn = fn
    def __get__(self, obj, cls):
        if obj is not None:
            return lambda *args, **kwds: self.fn(obj, *args, **kwds)
        else:
            return lambda *args, **kwds: self.fn(cls, *args, **kwds)
  
class UKIDSS(object):
 
    @class_or_instance
    def query(self):
        if self is UKIDSS:
            print("Calling query as class method")
        else:
            print("Calling query as instance method")