def send_unavailable(from, to)
      available = router.available_resources(from, to)
      stanzas = available.map {|stream| unavailable(stream.user.jid) }
      broadcast_to_available_resources(stanzas, to)
    end
def send_unavailable(from, to)
      available = router.available_resources(from, to)
      stanzas = available.map {|stream| unavailable(stream.user.jid) }
      broadcast_to_available_resources(stanzas, to)
    end
Broadcast unavailable presence from the user's available resources to the
 recipient's available resources. Route the stanza to a remote server if
 the recipient isn't hosted locally.