public function get( $key )
	{
		$uri		= $this->getUriForKey( $key );
		if( !$this->isValidFile( $uri ) )
			return NULL;
		if( isset( $this->data[$key] ) )
			return $this->data[$key];
		$content	= FS_File_Editor::load( $uri );
		$value		= unserialize( $content );
		$this->data[$key]	= $value;
		return $value;
	}