def _updated_or_published(mf):
	"""
	get the updated date or the published date

	Args:
		mf: python dictionary of some microformats object

	Return: string containing the updated date if it exists, or the published date if it exists or None

	"""

	props =  mf['properties']

	# construct updated/published date of mf
	if 'updated' in props:
		return props['updated'][0]
	elif 'published' in props:
		return props['published'][0]
	else:
		return None