An ExceptionSet is a grouping of exception handlers which acts as a single handler. Within the group, the most recently added handler will be the last handler found during a handler search (in the case where more than one handler in the group is capable of handling a given exception).

	private
	add: initialize

	exceptionSelector	top
	, Return an exception set that contains the receiver and the argument exception. This is commonly used to specify a set of exception selectors for an exception handler.
	handles: Determine whether an exception handler will accept a signaled exception.

	private	top
	add:
	initialize

	exceptionInstantiator	top
	new Answer a new instance of the receiver (which is a class) with no indexable variables. Fail if the class is indexable.