public function append($key, $href, array $meta=[]) {
		Validator::checkMemberName($key);
		
		if (isset($this->links[$key]) === false) {
			$this->addLinksArray($key, new LinksArray());
		}
		elseif ($this->links[$key] instanceof LinksArray === false) {
			throw new DuplicateException('can not add to key "'.$key.'", it is not an array of links');
		}
		
		$this->links[$key]->add($href, $meta);
	}