code: def navactive(request, url, exact=0, use_resolver=1):
      
      if use_resolver:
          try:
              if url == resolve(request.path).url_name:
                  # Checks the url pattern in case a view_name is posted
                  return 'active'
              elif url == request.path:
                  # Workaround to catch URLs with more than one part, which don't
                  # raise a Resolver404 (e.g. '/index/info/')
                  match = request.path
              else:
                  return ''
          except Resolver404:
              # Indicates, that a simple url string is used (e.g. '/index/')
              match = request.path
      else:
          match = request.path
  
      if exact and url == match:
          return 'active'
      elif not exact and url in request.path:
          return 'active'
      return ''
docs: Returns ``active`` if the given URL is in the url path, otherwise ''.
  
      Usage::
  
          {% load libs_tags %}
          ...
          <li class="{% navactive request "/news/" exact=1 %}">
  
      :param request: A request instance.
      :param url: A string representing a part of the URL that needs to exist
        in order for this method to return ``True``.
      :param exact: If ``1`` then the parameter ``url`` must be equal to
        ``request.path``, otherwise the parameter ``url`` can just be a part of
        ``request.path``.
      :use_resolver: If ``0`` we will not try to compare ``url`` with existing
        view names but we will only compare it with ``request.path``.