Used to signal progress without requiring a specific receiver to notify. Caller/callee convention could be to simply count the number of signals caught or to pass more substantive information with #signal:.

	accessing	top
	amount
	amount:
	done
	done:
	extraParam
	extraParam:

	exceptionInstantiator	top
	signal:extra: TFEI - Signal the occurrence of an exceptional condition with a specified textual description.