is very general (independent of hierarchy), or if you want to trap people on a class tree...
obj isKindOf: CVLambda
sorry, but this even worse than using #isXXX
Hence my preference for askFor:
http://bugs.squeak.org/view.php?id=5319
anObject askFor: #isRectangle
where askFor: returns the value if it is defined and false otherwise.
Keith