code: function bind () {
      if (_bound) return
      let {sub, pub} = getSockets()
      sub.bindSync(`tcp://0.0.0.0:*`)
      pub.bindSync(`tcp://0.0.0.0:*`)
      _sub = sub
      _pub = pub
      _subPort = getSocketPort(_sub)
      _pubPort = getSocketPort(_pub)
      _bound = true
    }
docs: binds a new pair of pub/sub sockets to all the
  interfaces, on random ports
  @return {[type]} [description]