old_contents: from django import template
  from datetime import timedelta
  register = template.Library()
  
  @register.filter(expects_localtime=True)
  def relative_date_hours(value, arg):
      """add or substract a given number of hours from a datetime"""
      print "adding %s to timedelta" % value
      return value + timedelta(hours=arg)
  
new_contents: from django import template
  from datetime import timedelta
  register = template.Library()
  
  @register.filter(expects_localtime=True)
  def relative_date_hours(value, arg):
      """add or substract a given number of hours from a datetime"""
      return value + timedelta(hours=arg)
  
subject: remove debug print