code: def process_index(self, url, page):
          
  
          def scan(link):
              # Process a URL to see if it's for a package page
              if link.startswith(self.index_url):
                  parts = list(map(
                      urllib.parse.unquote, link[len(self.index_url):].split('/')
                  ))
                  if len(parts) == 2 and '#' not in parts[1]:
                      # it's a package page, sanitize and index it
                      pkg = safe_name(parts[0])
                      ver = safe_version(parts[1])
                      self.package_pages.setdefault(pkg.lower(), {})[link] = True
                      return to_filename(pkg), to_filename(ver)
              return None, None
  
          # process an index page into the package-page index
          for match in HREF.finditer(page):
              try:
                  scan(urllib.parse.urljoin(url, htmldecode(match.group(1))))
              except ValueError:
                  pass
  
          pkg, ver = scan(url)  # ensure this page is in the page index
          if pkg:
              # process individual package page
              for new_url in find_external_links(url, page):
                  # Process the found URL
                  base, frag = egg_info_for_url(new_url)
                  if base.endswith('.py') and not frag:
                      if ver:
                          new_url += '#egg=%s-%s' % (pkg, ver)
                      else:
                          self.need_version_info(url)
                  self.scan_url(new_url)
  
              return PYPI_MD5.sub(
                  lambda m: '<a href="%s#md5=%s">%s</a>' % m.group(1, 3, 2), page
              )
          else:
              return ""
docs: Process the contents of a PyPI page