def patch(namespace, name, value):

    """ rebind the 'name' on the 'namespace'  to the 'value',

        possibly and remember the original value. Multiple

        invocations to the same namespace/name pair will

        remember a list of old values.

    """

    nref = (namespace, name)

    orig = getattr(namespace, name)

    patched.setdefault(nref, []).append(orig)

    setattr(namespace, name, value)

    return orig