How to use the prefect.core.flow.Flow function in prefect

if self.call_count < 2:
                    self.call_count += 1
                    # add small delta to trigger "naptime"
                    return [pendulum.now("utc").add(seconds=0.05)]
                else:
                    raise SyntaxError("Cease scheduling!")

        class StatefulTask(Task):
            call_count = 0

            def run(self):
                self.call_count += 1

        t = StatefulTask()
        schedule = MockSchedule()
        f = Flow(name="test", tasks=[t], schedule=schedule)
        with pytest.raises(SyntaxError, match="Cease"):
            f.run()
        assert t.call_count == 2

def test_sorted_tasks_with_ambiguous_sort():
    """
    t1 -> bottleneck
    t2 -> bottleneck
    t3 -> bottleneck
           bottleneck -> t4
           bottleneck -> t5
           bottleneck -> t6
    """

    f = Flow(name="test")
    t1 = Task("1")
    t2 = Task("2")
    t3 = Task("3")
    t4 = Task("4")
    t5 = Task("5")
    t6 = Task("6")
    bottleneck = Task("bottleneck")
    f.add_edge(t1, bottleneck)
    f.add_edge(t2, bottleneck)
    f.add_edge(t3, bottleneck)
    f.add_edge(bottleneck, t4)
    f.add_edge(bottleneck, t5)
    f.add_edge(bottleneck, t6)

    tasks = f.sorted_tasks()
    assert set(tasks[:3]) == set([t1, t2, t3])

def test_load_accepts_name_and_sluggified_name(self):
        t = Task(name="foo")
        f = Flow("I aM a-test!", tasks=[t])

        with tempfile.TemporaryDirectory() as tmpdir:
            with set_temporary_config({"home_dir": tmpdir}):
                f.save()

                new_obj_from_name = Flow.load("I aM a-test!")
                new_obj_from_slug = Flow.load("i-am-a-test")

        assert isinstance(new_obj_from_name, Flow)
        assert len(new_obj_from_name.tasks) == 1
        assert list(new_obj_from_name.tasks)[0].name == "foo"
        assert list(new_obj_from_name.tasks)[0].slug == t.slug
        assert new_obj_from_name.name == "I aM a-test!"

        assert isinstance(new_obj_from_slug, Flow)
        assert len(new_obj_from_slug.tasks) == 1
        assert list(new_obj_from_slug.tasks)[0].name == "foo"
        assert list(new_obj_from_slug.tasks)[0].slug == t.slug
        assert new_obj_from_slug.name == "I aM a-test!"

def test_update_with_constants():
    with Flow("math") as f:
        x = Parameter("x")
        d = x["d"] + 4

    new_flow = Flow("test")
    new_flow.update(f)

    flow_state = new_flow.run(x=dict(d=42))
    assert flow_state.is_successful()
    assert flow_state.result[d].result == 46

def test_binding_a_task_in_context_adds_it_to_flow():
    with Flow() as flow:
        t = Task()
        assert t not in flow.tasks
        t.bind()
        assert t in flow.tasks

def test_flow_dot_run_persists_scheduled_start_time_across_retries(self):
        # start very soon
        start_time = pendulum.now().add(seconds=0.2)

        @task(max_retries=1, retry_delay=datetime.timedelta(0))
        def report_start_time():
            if prefect.context.task_run_count == 1:
                raise ValueError("I'm not ready to tell you the start time yet")
            return prefect.context.scheduled_start_time

        f = Flow(
            name="test",
            tasks=[report_start_time],
            schedule=prefect.schedules.Schedule(
                clocks=[prefect.schedules.clocks.DatesClock(dates=[start_time])]
            ),
        )
        state = f.run()
        assert state.result[report_start_time].result is start_time

def test_context_manager_is_properly_applied_to_tasks():
    t1 = Task()
    t2 = Task()
    t3 = Task()
    with Flow(name="test") as f1:
        with Flow(name="test") as f2:
            t2.bind()
        t1.bind()

    with pytest.raises(ValueError):
        t3.bind()

    assert f1.tasks == set([t1])
    assert f2.tasks == set([t2])

def test_flow_parameters():
    f = Flow(name="test")
    x = Parameter("x")
    y = Parameter("y", default=1)
    f.add_task(x)
    f.add_task(y)

    assert f.parameters() == {x, y}

def test_create_flow_without_state_handler(self):
        assert Flow().state_handlers == []

def test_copy_creates_new_id():
    f = Flow()
    f2 = f.copy()
    assert f.id != f2.id