Please explain about df_no_age in concatenating exercise. it is not define in the before sections.
Thanks for reaching out.
Indeed, it has not been explained - it is an exercise for you to try out replicate the reordering and concatenation operations described in that section of the SQL+Tableai+Python course.
Please remember that unless specified, at this stage of this course, we ask you to use no other methods, functions or techniques other than the ones that have been presented and elaborated in the lectures thus far!
Hope this helps but please feel free to get back to us should you need further assistance. Thank you.