public function add( $data = null, $value = null ) {

		if ( null !== $value ) {
			$data = array( $data => $value );
		}

		$data = (array) $this->do_hook( 'add', $data );

		if ( empty( $data ) ) {
			return 0;
		}

		$params = array(
			'pod'                 => $this->pod,
			'data'                => $data,
			'allow_custom_fields' => true,
		);

		return $this->api->save_pod_item( $params );
	}