old_contents: from django import template
  
  
  register = template.Library()
  
  @register.filter
  def timezone_format(value):
  	""" Check the value of the timezeone offset and, if postive, add a plus sign"""
  	try:
  		if int(value) > 0:
  			value = '+' + str(value)
  	except:
  		pass
  	return value
new_contents: from django import template
  
  
  register = template.Library()
  
  @register.filter
  def timezone_format(value):
  	""" Check the value of the timezeone offset and, if postive, add a plus sign"""
  	try:
  		if int(value) > 0:
  			value = '+' + str(value)
  	except:
  		value = None
  	return value
subject: update timezone_format custom filter to display None if exception