Return the TagSemanticTag for the given tag name and semantic tag URI, or None.

		:param tag_name: the name of the tag to look for
		:type tag_name: string
		:param tag_URI: the name of the tag to look for
		:type tag_URI: string

		:returns: the TagSemanticTag for the given tag name and semantic tag URI, or None
			if there is no TagSemanticTag for those semantic tag and tag names
		:rtype: ckan.model.tag_semanictag.TagSemanticTag

def by_name(self, tag_name, semantictag_URI,
			autoflush=True):
		'''Return the TagSemanticTag for the given tag name and semantic tag URI, or None.

		:param tag_name: the name of the tag to look for
		:type tag_name: string
		:param tag_URI: the name of the tag to look for
		:type tag_URI: string

		:returns: the TagSemanticTag for the given tag name and semantic tag URI, or None
			if there is no TagSemanticTag for those semantic tag and tag names
		:rtype: ckan.model.tag_semanictag.TagSemanticTag

		'''
		
		query = (meta.Session.query(TagSemanticTag)
					.filter(_tag.Tag.name==tag_name)
					.filter(SemanticTag.URI==semantictag_URI))
		query = query.autoflush(autoflush)
		return query.one()[0]