public static function createIcon(string $icon, array $arguments = null) {
		$element = Html::el("i");
		
		if($icon == "b" or $icon == "l" or $icon == "s" or $icon == "r") {
			// Markup of icon which use Font Awesome 5.
			$class = ["fa".$icon];
		} else {
			// Markup of icon which use Font Awesome 4.
			$class = ["fa fa-".$icon];
		}
		
		if(isset($arguments)) {
			foreach($arguments as $argument) {
				$class[] = "fa-".$argument;
			}
		}
		
		$element->addAttributes(["class" => $class, "aria-hidden" => "true"]);
		return $element;
	}