public function __isset( $childName )
    {
        // Iterate over all nodes and check if a child with the requested name
        // exists.
        foreach ( $this->nodes as $node )
        {
            if ( isset( $node->$childName ) )
            {
                // We found something, so that we can immediatly exit with
                // true. The general count is out of interest here.
                return true;
            }
        }

        // Return false, if no such property could be found before...
        return false;
    }