old_contents: from django import template
  register = template.Library()
  
  # Don't really like using relative imports, but no choice here!
  from ..helpers import nice_repr, iso8601_repr, total_seconds as _total_seconds
  
  @register.filter(name='timedelta')
  def timedelta(value, display="long"):
      return nice_repr(value, display)
  
  @register.filter(name='iso8601')
  def iso8601(value):
      return iso8601_repr(value)
  
  @register.filter(name='total_seconds')
  def total_seconds(value):
      return _total_seconds(value)
  
  @register.filter(name='total_seconds_sort')
  def total_seconds(value, places=10):
      return ("%0" + str(places) + "i") % _total_seconds(value)
  
  
new_contents: from django import template
  register = template.Library()
  
  # Don't really like using relative imports, but no choice here!
  from ..helpers import nice_repr, iso8601_repr, total_seconds as _total_seconds
  
  @register.filter(name='timedelta')
  def timedelta(value, display="long"):
      if value is None:
          return value
      return nice_repr(value, display)
  
  @register.filter(name='iso8601')
  def iso8601(value):
      if value is None:
          return value
      return iso8601_repr(value)
  
  @register.filter(name='total_seconds')
  def total_seconds(value):
      if value is None:
          return value
      return _total_seconds(value)
  
  @register.filter(name='total_seconds_sort')
  def total_seconds(value, places=10):
      if value is None:
          return value
      return ("%0" + str(places) + "i") % _total_seconds(value)
  
  
subject: Allow for calling our filters on objects that are None