text: import re
  
  from django import template
  from django.core.urlresolvers import reverse, NoReverseMatch
  
  register = template.Library()
  
  
  @register.simple_tag(takes_context=True)
  def active(context, pattern_or_urlname):
      try:
          pattern = '^' + reverse(pattern_or_urlname)
      except NoReverseMatch:
          pattern = pattern_or_urlname
      path = context['request'].path
      if re.search(pattern, path):
          return ' active'
      return ''
  