[AIRFLOW-XXX] Give a clue what the 'ds' variable is
[AIRFLOW-XXX] Give a clue what the 'ds' variable is

It's not explained anywhere else in the
tutorial...

Closes #2679 from tgs/patch-1

(cherry picked from commit 2fef9152bef38cc04885f387cd250c6a313d5295)
Signed-off-by: Bolke de Bruin <17f52a69a3ba26c79c8a88ef8c1f26312d9cbf0e@xs4all.nl>

Twistbioscience/incubator-airflow,Twistbioscience/incubator-airflow,Twistbioscience/incubator-airflow,Twistbioscience/incubator-airflow