Data access in task_name.output when expanding

[dpro-shc]

Let's say we have two tasks, extract and load where extract returns a list of json objects say, [{"foo":"dan","bar":"shc"},{"foo":"alf","bar":"shc"}], and load expands on the output of extract

tasks:
    extract
      operator: airflow.operators.python.PythonOperator
      python_callable_name: extract_fn
      python_callable_file: /usr/local/airflow/dags/extractLoad/utils/python_callables/bronze_tasks.py

    load:
      operator: airflow.operators.python.PythonOperator
      python_callable_name: load_fn
      python_callable_file: /usr/local/airflow/dags/extractLoad/utils/python_callables/bronze_tasks.py
      expand:
        input: extract.output
      dependencies: [extract]

This works, but it's not ideal. The solution is sort of clunky and the internals are obscured-- I have to make the signature of the load task callable load_fn(input), one argument and unpack the values in the function. I'm proposing this functionality:

tasks:
    extract
      operator: airflow.operators.python.PythonOperator
      python_callable_name: extract_fn
      python_callable_file: /usr/local/airflow/dags/extractLoad/utils/python_callables/bronze_tasks.py

    load:
      operator: airflow.operators.python.PythonOperator
      python_callable_name: load_fn
      python_callable_file: /usr/local/airflow/dags/extractLoad/utils/python_callables/bronze_tasks.py
      expand:
        foo: extract.output.foo
        bar: extract.output.bar
      dependencies: [extract]
      

so that I can leave the signature of the load callable load_fn(foo,bar).