Help please, with this code fragment

[MikeK]

The following code fragment, from Eckel's upcoming "Thinking in
Python",
does not work under Python 2.1, and the problem appears to be related
to
namespaces.  I've worked with this for a couple of hours now, trying
to
come up with a workable alternative/understanding using my limited
knowledge of Python.  Could someone give me a hand?

The code is supposed to take a class method and wrap it in code that
uses
a class object-level mutex to synchronize the getting/setting of some
data that might be get/set by multiple callers of its methods.  Python
2.1 has trouble with the 'method' argument to synchronized(), telling
me that when used in function 'f()', it is not found.  I have a
general understanding that this is due to the changes to namespaces in
2.1, but don't know how to change the code to get the equivalent
functionality.

===Begin code===
import threading

def synchronized(method):
    def f(*args):
        self = args[0]
        self.mutex.acquire()
        try:
            return apply(method, args)
        finally:
            self.mutex.release()
    return f
===End code===