public function mask($string, $repeat = true, $numShow = 4, $maskChar = 'x')
	{
		#$this->debug->log('func_start',__FUNCTION__);
		if (strlen($string) > $numShow) {
			$string = ( $repeat
					? str_repeat($maskChar, strlen($string)-$numShow)
					: $maskChar
				)
				.substr($string, -$numShow);
		}
		#$this->debug->groupEnd();
		return $string;
	}