title: Getting Error in airflow DAG unsupported operand type(s) for >>: 'list' and 'list'. Sequential and Parallel execution of tasks
body: <p>I am new to Apache airflow and DAG. There are total 6 tasks in the DAG (task1, task2, task3, task4, task5, task6). But at the time of running the DAG we are getting the error below.</p>
  <p><strong>DAG unsupported operand type(s) for &gt;&gt;: 'list' and 'list'</strong></p>
  <p>Below is my code for the DAG. Please help. I am new to airflow.</p>
  <pre><code>from airflow import DAG
  from datetime import datetime
  from airflow.providers.databricks.operators.databricks import DatabricksSubmitRunOperator
  
  
  default_args = {
      'owner': 'airflow',
      'depends_on_past': False
  }
  
  dag = DAG('DAG_FOR_TEST',default_args=default_args,schedule_interval=None,max_active_runs=3, start_date=datetime(2020, 7, 14)) 
  
  
  #################### CREATE TASK #####################################   
  
  task_1 = DatabricksSubmitRunOperator(
      task_id='task_1',
      databricks_conn_id='connection_id_details',
      existing_cluster_id='{{ dag_run.conf.clusterId }}',
      libraries= [
          {
          'jar': 'dbfs:/task_1/task_1.jar'
          }        
          ],
      spark_jar_task={
          'main_class_name': 'com.task_1.driver.TestClass1',
          'parameters' : [
              '{{ dag_run.conf.json }}'       
          ]
      }
  )
  
  
  
      
  task_2 = DatabricksSubmitRunOperator(
      task_id='task_2',
      databricks_conn_id='connection_id_details',
      existing_cluster_id='{{ dag_run.conf.clusterId }}',   
      libraries= [
          {
          'jar': 'dbfs:/task_2/task_2.jar'
          }        
          ],
      spark_jar_task={
          'main_class_name': 'com.task_2.driver.TestClass2',
          'parameters' : [
              '{{ dag_run.conf.json }}'                               
          ]
      }
  )
      
  task_3 = DatabricksSubmitRunOperator(
      task_id='task_3',
      databricks_conn_id='connection_id_details',
      existing_cluster_id='{{ dag_run.conf.clusterId }}',   
      libraries= [
          {
          'jar': 'dbfs:/task_3/task_3.jar'
          }        
          ],
      spark_jar_task={
          'main_class_name': 'com.task_3.driver.TestClass3',
          'parameters' : [
              '{{ dag_run.conf.json }}'   
          ]
      }
  ) 
  
  task_4 = DatabricksSubmitRunOperator(
      task_id='task_4',
      databricks_conn_id='connection_id_details',
      existing_cluster_id='{{ dag_run.conf.clusterId }}',
      libraries= [
          {
          'jar': 'dbfs:/task_4/task_4.jar'
          }        
          ],
      spark_jar_task={
          'main_class_name': 'com.task_4.driver.TestClass4',
          'parameters' : [
              '{{ dag_run.conf.json }}'   
          ]
      }
  ) 
  
  task_5 = DatabricksSubmitRunOperator(
      task_id='task_5',
      databricks_conn_id='connection_id_details',
      existing_cluster_id='{{ dag_run.conf.clusterId }}',
      libraries= [
          {
          'jar': 'dbfs:/task_5/task_5.jar'
          }        
          ],
      spark_jar_task={
          'main_class_name': 'com.task_5.driver.TestClass5',
          'parameters' : [
              'json ={{ dag_run.conf.json }}' 
          ]
      }
  ) 
  
  task_6 = DatabricksSubmitRunOperator(
      task_id='task_6',
      databricks_conn_id='connection_id_details',
      existing_cluster_id='{{ dag_run.conf.clusterId }}',
      libraries= [
          {
          'jar': 'dbfs:/task_6/task_6.jar'
          }        
          ],
      spark_jar_task={
          'main_class_name': 'com.task_6.driver.TestClass6',
          'parameters' : ['{{ dag_run.conf.json }}'   
          ]
      }
  ) 
  
  #################### ORDER OF OPERATORS ###########################  
   
      task_1.dag = dag
      task_2.dag = dag
      task_3.dag = dag
      task_4.dag = dag
      task_5.dag = dag
      task_6.dag = dag
  
  task_1 &gt;&gt; [task_2 , task_3] &gt;&gt; [ task_4 , task_5 ] &gt;&gt; task_6 
  </code></pre>