Use this around code in your package repository that is loading a
        package, for example from file or cache.

def package_loading(self):
        """Use this around code in your package repository that is loading a
        package, for example from file or cache.
        """
        t1 = time.time()
        yield None

        t2 = time.time()
        self.package_load_time += t2 - t1