from functools import wraps

from threading import RLock

def lock_for_object(obj, locks={}):

return locks.setdefault(id(obj), RLock())

def synchronized(call):

assert call.__code__.co_varnames[0] in ['self', 'cls']

@wraps(call)

def inner(*args, **kwds):

with lock_for_object(args[0]):

return call(*args, **kwds)

return inner