'Brokers should register themselves with priorities as follows:
- 1000-1999: Content-agnostic raw connections
- 3000-3999: Secure network layers: VPNs, Tor, I2P, ...
- 5000-5999: Proxies required to reach the wider Internet
- 7000-7999: Protocol enhancments (non-security related)
- 9000-9999: Security-related protocol enhancements'

def register_broker(self, priority, cb):

    self.brokers.append((priority, cb(master=self)))
    self.brokers.sort()
    self.brokers.reverse()
