code: def display_candidates(self, candidates, pdf_file=None):
          
          if not pdf_file:
              pdf_file = os.path.join(
                  self.pdf_path, candidates[0][0].context.sentence.document.name
              )
              if os.path.isfile(pdf_file + ".pdf"):
                  pdf_file += ".pdf"
              elif os.path.isfile(pdf_file + ".PDF"):
                  pdf_file += ".PDF"
              else:
                  logger.error("display_candidates failed: pdf file missing.")
          boxes = [
              get_box(mention.context) for c in candidates for mention in c.get_mentions()
          ]
          imgs = self.display_boxes(pdf_file, boxes, alternate_colors=True)
          return display(*imgs)
docs: Displays the bounding boxes corresponding to candidates on an image of the pdf
          boxes is a list of 5-tuples (page, top, left, bottom, right)