Form_Settings_Page::add_tab( string $id, array $args = array() )

	public function add_tab( $id, $args = array() ) {
		$prefix = $this->manager->get_prefix();

		if ( 0 !== strpos( $id, $prefix ) ) {
			$id = $prefix . $id;
		}

		$this->tabs[ $id ] = wp_parse_args( $args, array(
			'title'            => '',
			'rest_description' => '',
		) );

		$services = array(
			'ajax'          => $this->manager->ajax(),
			'assets'        => $this->manager->assets(),
			'error_handler' => $this->manager->error_handler(),
		);

		$this->tabs[ $id ]['field_manager'] = new Field_Manager( $this->manager->get_prefix(), $services, array(
			'get_value_callback_args'    => array( $id ),
			'update_value_callback_args' => array( $id, '{value}' ),
			'name_prefix'                => $id,
		) );
	}