arcgis server - How to convert a String variable to a Raster datatype using Calculate Value

I have a GP service I would like to consume in a Flex application, but one of the input data types can be a raster. ArcGIS Server does not support a raster data type as an input parameter, but according to their documentation here - Input and Output Data Types - you can create a variable in your model/script of type String and convert that into the data type your model requires. In their example they use an Areal Unit, but I need to convert to a raster dataset/raster layer. How would I implement this?

Answer

If I'm reading the docs correctly, isn't it just a matter of selecting "Raster Dataset" from the Data type dropdown and feeding in your string value as the Expression, and that will convert it from string to raster?