onInstanceBoundChange(Type, handler, [queueName])

Register an event handler on the object Type that fires when instances of the type become bound (the first handler is added) or unbound (the last remaining handler is removed). The function passed as handler will be called with the instance as the first argument and true as the second argument when instance gains its first binding, and called with false when instance loses its last binding.

Person = DefineMap.extend({ ... });

var person = Person({});
var handler = function(instance, newVal) {
    console.log(instance, "bound state is now", newVal);
};
var keyHandler = function() {};

canReflect.onInstanceBoundChange(Person, handler);
canReflect.onKeyValue(obj, "name", keyHandler);  // logs person Bound state is now true
canReflect.offKeyValue(obj, "name", keyHandler);  // logs person Bound state is now false