Inject additional tags into the list already supplied to LogEvent.

def _tags(self, tags, event_code):
        ''' Inject additional tags into the list already supplied to LogEvent.
        '''
        tags_list = []
        if tags is not None:
            tags_list += list(tags)
        tags_list.append("event_id:{event_id}".format(event_id=event_code))
        return tags_list