How to use the flower.actor.spawn function in flower

sources = []
        def f():
            while True:
                source, msg = receive()
                if not msg:
                    break
                if source.ref not in sources:
                    sources.append(source.ref)
                messages.append(msg)

        def f1(ref):
            msg = ['hello', ' ', 'world']
            for s in msg:
                send(ref, s)

        pid0 = spawn(f)
        pid1 = spawn(f1, pid0)

        core.run()

        assert messages == ['hello', ' ', 'world']
        assert sources == [3]

def test_registered(self):
        r_list = []
        def f():
            print("ici %s" % registered())
            print(registry._by_ref)
            [r_list.append(r) for r in registered()]

        pid = spawn(f)
        register("b", pid)
        register("a", pid)



        assert 'a' in registry
        assert 'b' in registry
        assert registered(pid) == ['a', 'b']

        pid.actor.switch()
        assert r_list == ['a', 'b']

def test_send_after(self):
        r_list = []
        def f():
            receive()
            r_list.append(time.time())

        ref = spawn(f)
        start = time.time()
        send_after(0.3, ref, None)

        core.run()

        end = r_list[0]
        diff = end - start
        assert 0.29 <= diff <= 0.31

def test_simple(self):
        def f(): return

        pid = spawn(f)
        register("test", pid)

        assert pid in registry
        assert "test" in registry
        assert registry["test"] ==  pid
        assert registry[pid] == ["test"]

        del registry[pid]
        assert registry["test"] is None

        core.run()

sources.append(source.ref)
                messages.append(msg)

        def f1(ref):
            msg = ['hello', 'world']
            for s in msg:
                send(ref, s)

        def f2(ref):
            msg = ['brave', 'new', 'world', '']
            for s in msg:
                send(ref, s)

        pid0 = spawn(f)
        pid1 = spawn(f1, pid0)
        pid2 = spawn(f2, pid0)

        core.run()

        assert len(messages) == 5
        assert sources == [5, 6]

def test_share_registry(self):
        r = Registry()

        def f(): return
        pid = spawn(f)
        register("test1", pid)

        assert "test1" in registry
        assert registry["test1"] is pid
        assert "test1" in r
        assert r["test1"] == registry["test1"]

if source.ref not in sources:
                    sources.append(source.ref)
                messages.append(msg)

        def f1(ref):
            msg = ['hello', 'world']
            for s in msg:
                send(ref, s)

        def f2(ref):
            msg = ['brave', 'new', 'world', '']
            for s in msg:
                send(ref, s)

        pid0 = spawn(f)
        pid1 = spawn(f1, pid0)
        pid2 = spawn(f2, pid0)

        core.run()

        assert len(messages) == 5
        assert sources == [5, 6]

break
                if source.ref not in sources:
                    sources.append(source.ref)
                messages.append(msg)

        def f1(ref):
            msg = ['hello', 'world']
            for s in msg:
                send(ref, s)

        def f2(ref):
            msg = ['brave', 'new', 'world', '']
            for s in msg:
                send(ref, s)

        pid0 = spawn(f)
        pid1 = spawn(f1, pid0)
        pid2 = spawn(f2, pid0)

        core.run()

        assert len(messages) == 5
        assert sources == [5, 6]

def f():
            while True:
                source, msg = receive()
                if not msg:
                    break
                if source.ref not in sources:
                    sources.append(source.ref)
                messages.append(msg)

        def f1(ref):
            msg = ['hello', ' ', 'world']
            for s in msg:
                send(ref, s)

        pid0 = spawn(f)
        pid1 = spawn(f1, pid0)

        core.run()

        assert messages == ['hello', ' ', 'world']
        assert sources == [3]

def test_simple(self):
        r_list = []
        def f():
            r_list.append(True)

        pid = spawn(f)
        assert isinstance(pid, ActorRef)
        assert pid.ref == 0
        assert hasattr(pid.actor, 'mailbox')

        sleep(0.1)
        core.run()

        assert r_list == [True]
        assert pid.actor is None
        assert pid.is_alive is False