multidimensional_get example

        $undefined     = new stdClass();
        $needs_preview = ( $undefined !== $this->post_value( $undefined ) );
        $value         = null;

        // Since no post value was defined, check if we have an initial value set.         if ( ! $needs_preview ) {
            if ( $this->is_multidimensional_aggregated ) {
                $root  = self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['root_value'];
                $value = $this->multidimensional_get( $root, $this->id_data['keys'], $undefined );
            } else {
                $default       = $this->default;
                $this->default = $undefined; // Temporarily set default to undefined so we can detect if existing value is set.                 $value         = $this->value();
                $this->default = $default;
            }
            $needs_preview = ( $undefined === $value ); // Because the default needs to be supplied.         }

        // If the setting does not need previewing now, defer to when it has a value to preview.         if ( ! $needs_preview ) {