docs: def combine_pdf_as_bytes(pdfs: List[BytesIO]) -> bytes:
      """Combine PDFs and return a byte-string with the result.
  
      Arguments
      ---------
      pdfs
          A list of BytesIO representations of PDFs
  
      """
      writer = PdfWriter()
      for pdf in pdfs:
          writer.addpages(PdfReader(pdf).pages)
      bio = BytesIO()
      writer.write(bio)
      bio.seek(0)
      output = bio.read()
      bio.close()
      return output