FluentDOM\Query::toggleClass PHP Method

    public function toggleClass($class, $switch = NULL)
    {
        $callback = Constraints::isCallable($class);
        $this->each(function (\DOMElement $node, $index) use($class, $switch, $callback) {
            if ($callback) {
                $classString = $callback($node, $index, $node->getAttribute('class'));
            } else {
                $classString = $class;
            }
            if (empty($classString) && !(bool) $switch) {
                if ($node->hasAttribute('class')) {
                    $node->removeAttribute('class');
                }
            } else {
                $modified = $this->changeClassString($node->getAttribute('class'), $classString, $switch);
                if (FALSE !== $modified) {
                    if (empty($modified)) {
                        $node->removeAttribute('class');
                    } else {
                        $node->setAttribute('class', $modified);
                    }
                }
            }
        }, TRUE);
        return $this;
    }