old_contents: from datetime import datetime
  from airflow.operators.docker_operator import DockerOperator
  from airflow.models import DAG, Variable
  import utils.helpers as helpers
  import os
  
  args = {
      'owner': 'airflow',
      'depends_on_past': False,
      'start_date': datetime.strptime('Dec 1 2016', '%b %d %Y'),
      'retries': 1,
  }
  
  dag = DAG(dag_id='cochrane_reviews',
            default_args=args,
            max_active_runs=1,
            schedule_interval='@monthly')
  
  collector_task = DockerOperator(
      task_id='cochrane_reviews_collector',
      dag=dag,
      image='okibot/collectors:latest',
      force_pull=True,
      environment={
          'WAREHOUSE_URL': helpers.get_postgres_uri('warehouse_db'),
          'COCHRANE_ARCHIVE_URL': Variable.get('COCHRANE_ARCHIVE_URL'),
          'LOGGING_URL': Variable.get('LOGGING_URL'),
          'PYTHON_ENV': Variable.get('ENV'),
          'FERNET_KEY': os.environ['FERNET_KEY'],
          'DOCKER_API_VERSION': Variable.get('DOCKER_API_VERSION'),
      },
      command='make start cochrane_reviews'
  )
  
  processor_task = DockerOperator(
      task_id='cochrane_reviews_processor',
      dag=dag,
      image='okibot/processors:latest',
      force_pull=True,
      environment={
          'WAREHOUSE_URL': helpers.get_postgres_uri('warehouse_db'),
          'DATABASE_URL': helpers.get_postgres_uri('api_db'),
          'EXPLORERDB_URL': helpers.get_postgres_uri('explorer_db'),
          'LOGGING_URL': Variable.get('LOGGING_URL'),
          'FERNET_KEY': os.environ['FERNET_KEY'],
          'DOCKER_API_VERSION': Variable.get('DOCKER_API_VERSION'),
      },
      command='make start cochrane_reviews'
  )
  
  processor_task.set_upstream(collector_task)
  
new_contents: from datetime import datetime
  from airflow.operators.docker_operator import DockerOperator
  from airflow.models import DAG, Variable
  import utils.helpers as helpers
  import os
  
  args = {
      'owner': 'airflow',
      'depends_on_past': False,
      'start_date': datetime.strptime('Dec 1 2016', '%b %d %Y'),
      'retries': 1,
  }
  
  dag = DAG(dag_id='cochrane_reviews',
            default_args=args,
            max_active_runs=1,
            schedule_interval='@monthly')
  
  collector_task = DockerOperator(
      task_id='cochrane_reviews_collector',
      dag=dag,
      image='okibot/collectors:latest',
      force_pull=True,
      api_version='1.23',
      environment={
          'WAREHOUSE_URL': helpers.get_postgres_uri('warehouse_db'),
          'COCHRANE_ARCHIVE_URL': Variable.get('COCHRANE_ARCHIVE_URL'),
          'LOGGING_URL': Variable.get('LOGGING_URL'),
          'PYTHON_ENV': Variable.get('ENV'),
          'FERNET_KEY': os.environ['FERNET_KEY'],
      },
      command='make start cochrane_reviews'
  )
  
  processor_task = DockerOperator(
      task_id='cochrane_reviews_processor',
      dag=dag,
      image='okibot/processors:latest',
      force_pull=True,
      api_version='1.23',
      environment={
          'WAREHOUSE_URL': helpers.get_postgres_uri('warehouse_db'),
          'DATABASE_URL': helpers.get_postgres_uri('api_db'),
          'EXPLORERDB_URL': helpers.get_postgres_uri('explorer_db'),
          'LOGGING_URL': Variable.get('LOGGING_URL'),
          'FERNET_KEY': os.environ['FERNET_KEY'],
      },
      command='make start cochrane_reviews'
  )
  
  processor_task.set_upstream(collector_task)
  
subject: Set Docker API version in the DockerOperator params