public static function currency($number, $currency = null, array $options = []) {
		$defaults = [
			'positive' => '+', 'signed' => false
		];
		$options += $defaults;
		$sign = '';
		if ($number > 0 && !empty($options['signed'])) {
			$sign = $options['positive'];
		}
		return $sign . parent::currency($number, $currency, $options);
	}