public function walk($callback)
	{
		//print_r($this->_data);
		//exit;
		
		foreach ($this->_data as $key => $value)
		{
			if (is_object($value))
			{
				$value->walk($callback);
			}
			else if (is_array($value))
			{
				foreach ($value as $skey => $svalue)
				{
					if (is_object($svalue))
					{
						$svalue->walk($callback);
					}
					else
					{
						$this->_data[$key][$skey] = call_user_func($callback, $this->resource(), $key, $svalue);
					}
				}
			}
			else
			{
				$this->_data[$key] = call_user_func($callback, $this->resource(), $key, $value);
			}
		}
	}