fic handler and the set of
instances to send to that handler. Whenever Mixer processes an incoming call, it invokes the indicated handler and gives it the specific set of instances for processing.</p><p>Rules contain matching predicates. A predicate is an attribute expression which returns a true/false value. A rule only takes effect if its predicate expression returns true. Otherwise, it’s like the rule didn’t exist and the indicated handler isn’t invoked.</p><h2 id=future>Future</h2><p>We are workin