public function post_value( $setting, $default = null ) {
		$post_values = $this->unsanitized_post_values();
		if ( ! array_key_exists( $setting->id, $post_values ) ) {
			return $default;
		}
		$value = $post_values[ $setting->id ];
		$valid = $setting->validate( $value );
		if ( is_wp_error( $valid ) ) {
			return $default;
		}
		$value = $setting->sanitize( $value );
		if ( is_null( $value ) || is_wp_error( $value ) ) {
			return $default;
		}
		return $value;
	}