rule exampleTrafo
	transform d : Source!Domain
	to d : Target!Domain{

	var choice = "bigDecision";

	switch(choice){
		case "bigDecision" : 
			var temp = createSomething();
			if(not temp.isDefined())
				"ohh boy".println();
	}
}

operation createSomething() : Target!Element1{
	var returnValue = new Target!Element1;
	if(returnValue.isDefined())
		"I'm ready to go".println();
	return returnValue;
}