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"""
Example LatestOnlyOperator and TriggerRule interactions
"""
import datetime as dt

import airflow
from airflow.models import DAG
from airflow.operators.dummy_operator import DummyOperator
from airflow.operators.latest_only_operator import LatestOnlyOperator
from airflow.utils.trigger_rule import TriggerRule

dag = DAG(
    dag_id='latest_only_with_trigger',
    schedule_interval=dt.timedelta(hours=4),
    start_date=airflow.utils.dates.days_ago(2),
)

latest_only = LatestOnlyOperator(task_id='latest_only', dag=dag)
task1 = DummyOperator(task_id='task1', dag=dag)
task2 = DummyOperator(task_id='task2', dag=dag)
task3 = DummyOperator(task_id='task3', dag=dag)
task4 = DummyOperator(task_id='task4', dag=dag, trigger_rule=TriggerRule.ALL_DONE)

latest_only >> task1 >> [task3, task4]
task2 >> [task3, task4]
