The essence is:
def receiver(sender, arg1, arg2):
print arg1, arg2
def otherReceiver(arg1, arg2):
if arg1=='oNOerror': sys.exit(1)
dispatcher.send('foo', sender='ninja', arg1='yaysuccess', arg2='whatever')
dispatcher.send('foo', sender='phb', arg1='oNOerror', arg2=123)
#==> yaysuccess whatever
#==> eek, error
Signals can be any (hashable?) python object, as can senders.
Even if you think this is a bad way to design an app (signals going all over the place, confusing the call stack), you might find it useful if you don't know how to design your app. Do it with the event dispatch mechanism first, then look for all the places where signals are sent, and figure out how to get them upstream in the call stack from the code handling them.