def uuid4(self):
        """Provide unique id on per-request basis using UUID4.

        It's evaluated lazily on render.
        """
        try:
            self._uuid4
        except AttributeError:
            # evaluate on first access
            self._uuid4 = uuid.uuid4()

        return self._uuid4
Provide unique id on per-request basis using UUID4.

        It's evaluated lazily on render.
        
cherrypy/_cprequest.py