How to use the simgrid.Host.by_name function in simgrid

def __call__(self):

        fafard = Host.by_name("Fafard")
        ginette = Host.by_name("Ginette")
        boivin = Host.by_name("Boivin")

        this_actor.info("I'm a wizard! I can run a task on the Ginette host from the Fafard one! Look!")
        activity = this_actor.exec_init(48.492e6)
        activity.host = ginette
        activity.start()
        this_actor.info("It started. Running 48.492Mf takes exactly one second on Ginette (but not on Fafard).")

        this_actor.sleep_for(0.1)
        this_actor.info("Loads in flops/s: Boivin={:.0f}; Fafard={:.0f}; Ginette={:.0f}".format(boivin.load, fafard.load,
                                                                                                ginette.load))
        activity.wait()
        this_actor.info("Done!")

        this_actor.info("And now, harder. Start a remote task on Ginette and move it to Boivin after 0.5 sec")
        activity = this_actor.exec_init(73293500)
        activity.host = ginette

def __call__(self):

        fafard = Host.by_name("Fafard")
        ginette = Host.by_name("Ginette")
        boivin = Host.by_name("Boivin")

        this_actor.info("I'm a wizard! I can run a task on the Ginette host from the Fafard one! Look!")
        activity = this_actor.exec_init(48.492e6)
        activity.host = ginette
        activity.start()
        this_actor.info("It started. Running 48.492Mf takes exactly one second on Ginette (but not on Fafard).")

        this_actor.sleep_for(0.1)
        this_actor.info("Loads in flops/s: Boivin={:.0f}; Fafard={:.0f}; Ginette={:.0f}".format(boivin.load, fafard.load,
                                                                                                ginette.load))
        activity.wait()
        this_actor.info("Done!")

        this_actor.info("And now, harder. Start a remote task on Ginette and move it to Boivin after 0.5 sec")

this_actor.sleep_for(0.5)
        this_actor.info("I changed my mind, cancel!")
        activity.cancel()

        this_actor.info("Goodbye now!")


if __name__ == '__main__':
    e = Engine(sys.argv)
    if len(sys.argv) < 2:
        raise AssertionError("Usage: exec-async.py platform_file [other parameters]")

    e.load_platform(sys.argv[1])

    Actor.create("wait", Host.by_name("Fafard"), Waiter())
    Actor.create("monitor", Host.by_name("Ginette"), Monitor())
    Actor.create("cancel", Host.by_name("Boivin"), Canceller())

    e.run()