const {
    next: newMessage,
    subscribe: handleMessage,
    filter: filterMessage 
} = createSubject()
 
//do something
handleMessage(msg => bar(msg))
 
//Send message
newMessage({payload:'bar'})
 
//filter the subscription
const filtered = filterMessage(msg => payload==='foo')
 
//subscribe and get the subscription back
const subscription = filtered.subscribe(msg => foo(msg))
 
///unsubscribe
subscription.unsubscribe()