One of the powerful features of TSIPP is the rich textures - combining one or more colors to form very realistic wood, granite and marble patterns.
The bumpy shader makes a reference to another shader for colour information and adds roughness. I was intrigued to find out whether a reference to another bumpy shader would be supported, even building a chain of them. Indeed it is supported and is useful - the moonscape example above creates roughness at different levels with three bumpy shaders in a chain.