public function addNode( $nodeName, $nodeValue = false )
	{
		$newNode = new ADT_Graph_Node( $nodeName, $nodeValue );
		if( !$this->isNode( $newNode ) )
		{
			$this->nodes[] = $newNode;
			return $newNode;
		}
		else
			return $this->getNode( $nodeName );
	}