code: def sanitize_next_page_link(next_page_link, base_url):
      
  
      if not next_page_link.startswith(u'http'):
          if next_page_link.startswith(u'?'):
              # We have some "?current_page=2" scheme.
              next_page_link = base_url + next_page_link
  
          if next_page_link.startswith(u'/'):
              # We have a server-relative path.
  
              try:
                  proto, host_and_port, remaining = split_url(base_url)
  
              except:
                  LOGGER.error(u'Could not split “%s” to get schema/host parts, '
                               u'next_page_link “%s” will be unusable.',
                               base_url, next_page_link)
  
              else:
                  next_page_link = '{0}://{1}{2}'.format(proto,
                                                         host_and_port,
                                                         next_page_link)
          else:
              LOGGER.warning(u'Unimplemented scheme in '
                             u'next_page_link %s',
                             next_page_link)
  
      return next_page_link
docs: Convert relative links or query_string only links to absolute URLs.