vtkImplicitBoolean Nested Operations Example Needed

The https://vtk.org/doc/nightly/html/classvtkImplicitBoolean.html webpage mentions " You can use nested combinations of vtkImplicitFunction’s (and/or vtkImplicitBoolean) to create elaborate implicit functions".

Is there an example somewhere of how to perform the nested operations?

All of the examples that I can find use just one level of boolean operations. I’m interested in being able, for example, to union 2 spheres as givin in the ImplicitBoolean example (https://kitware.github.io/vtk-examples/site/Cxx/Filtering/ImplicitBoolean/) then take a 3rd body such as a plane and cut the tops off of the unioned sheres. So, this involves two different boolean operations UNION and DIFFERENCE. (The plane could theoretically be any other implicit function.)

Can someone point me in the right direction?