Context: I want to clean my data in a specific way because it has the same structure (different excel sheets).
I have done the cleaning for 1 sheet. it works great as expected. Now I want to merge all the excel sheets together while applying on each one of them the same transformation I did previously (pre-merge).
In other words: input sheet1->clean->input sheet2->clean same way->append rows below sheet1->input sheet 3->clean same way->append rows below sheet2(and sheet 1 obviously)....
Example in the image is a simplified version without cleaning applied.
