FluidXml\FluidInsertionHandler::insertIntegerString PHP Method

    protected function insertIntegerString($parent, $k, $v, $fn)
    {
        // The user has passed a node name without a node value:
        // [ 'element', ... ]
        $el = $this->createElement($v);
        $el = $fn($parent, $el);
        return [$el];
    }