code: def _update_page_resources(*, page, font, font_key, procset):
      
  
      if '/Resources' not in page:
          page['/Resources'] = pikepdf.Dictionary({})
      resources = page['/Resources']
      try:
          fonts = resources['/Font']
      except KeyError:
          fonts = pikepdf.Dictionary({})
      if font_key is not None and font_key not in fonts:
          fonts[font_key] = font
      resources['/Font'] = fonts
  
      # Reassign /ProcSet to one that just lists everything - ProcSet is
      # obsolete and doesn't matter but recommended for old viewer support
      resources['/ProcSet'] = procset
docs: Update this page's fonts with a reference to the Glyphless font