Use the blocks inside of your widget tree.

1. The first block "PDF_Merger_Binary" takes 2 pdf's as input (binary data) and merges them into one PDF. After that, it raises an event with the generated PDF so the parent can use it (E.g. store it in the database async).
2. The second block "PDF_Merger_Binary_WithDownload" does the same, with an extra feature that automatically downloads the PDF.