protected function _get_key($remove = false)
	{
		// get the current index information
		list($identifier, $sections, $index) = $this->_get_index();

		// get the key from the index
		$key = isset($index[$identifier][0]) ? $index[$identifier][0] : false;

		if ($remove === true)
		{
			if ( $key !== false )
			{
				unset($index[$identifier]);
				apc_store($this->config['cache_id'].$sections, $index);
			}
		}
		else
		{
			// create a new key if needed
			$key === false and $key = $this->_new_key();
		}

		return $key;
	}