public function appendAttribute($name, $value, $option = TRUE)
	{
		if (is_array($value)) {
			$prev = isset($this->attrs[$name]) ? (array)$this->attrs[$name] : [];
			$this->attrs[$name] = $value + $prev;

		} elseif ((string)$value === '') {
			$tmp = &$this->attrs[$name]; // appending empty value? -> ignore, but ensure it exists

		} elseif (!isset($this->attrs[$name]) || is_array($this->attrs[$name])) { // needs array
			$this->attrs[$name][$value] = $option;

		} else {
			$this->attrs[$name] = [$this->attrs[$name] => TRUE, $value => $option];
		}

		return $this;
	}