code: function(names, cb) {
        if (!cb) {
          cb = function() {};
        }
        if (!session.channels) {
          session.channels = [];
        }
        forceArray(names).forEach(function(name) {
          if (session.channels.indexOf(name) === -1) { // clients can only join a channel once
            session.channels.push(name);
            return ss.log.info('i'.green + ' subscribed sessionId '.grey + session.id + ' to channel '.grey + name);
          }
        });
        this._bindToSocket();
        return session.save(cb);
      }
docs: Subscribes the client to one or more channels