def branch_test(**kwargs):
  if int(kwargs['ds_nodash']) % 2 == 0:
    return 'even_day_task'
  else:
    return 'odd_day_task'


branch_task = BranchPythonOperator(task_id='branch_task',dag=dag,
       provide_context=True,
       python_callable=branch_test)


start_task >> branch_task >> even_day_task >> even_day_task2

branch_task >> odd_day_task >> odd_day_task2