code: function(port, host, opts) {
    if (!(this instanceof Connector)) {
      return new Connector(port, host, opts);
    }
  
    EventEmitter.call(this);
  
    this.opts = opts || {};
    this.port = port;
    this.host = host;
    this.useDict = opts.useDict;
    this.useProtobuf = opts.useProtobuf;
    this.handshake = new Handshake(opts);
    this.heartbeat = new Heartbeat(opts);
    this.distinctHost = opts.distinctHost;
    this.ssl = opts.ssl;
  
    this.switcher = null;
  }
docs: Connector that manager low level connection and protocol bewteen server and client.
  Develper can provide their own connector to switch the low level prototol, such as tcp or probuf.