[Pharo-project] about class abtractness

I would really like to have a way to specify that a class is abstract. For example I would like to be able to write a test as follow self assert: (Collection allSubclasses reject: [:each each isAbstract ]) new isEmpty now saying that isAbstract is if a class has one method sending subclassResponsibility is not really good for me. May be we could have something like isAbstract ^ self declaredAsAbstract or: [ (self whichSelectorsReferToSymbol: #subclassResponsibility) isEmpty not] Stef