old_contents: from django import template
  from django.core.urlresolvers import reverse
  
  register = template.Library()
  
  
  @register.filter
  def reverse_node(value):
      return reverse('nodes:node', kwargs={'guid': value})
  
  @register.filter
  def reverse_user(user_id):
      return reverse('users:user', kwargs={'guid': user_id})
  
new_contents: from django import template
  from django.core.urlresolvers import reverse
  
  register = template.Library()
  
  
  @register.filter
  def reverse_node(value):
      return reverse('nodes:node', kwargs={'guid': value})
  
  @register.filter
  def reverse_preprint(value):
      return reverse('preprints:preprint', kwargs={'guid': value})
  
  @register.filter
  def reverse_user(user_id):
      return reverse('users:user', kwargs={'guid': user_id})
  
subject: Add reverse preprint to node_extras