docs: function addConnection(conn) {
  
    this.emit('connect');
  
    function onInput(len) {
      this._stats.ibytes += len;
    }
  
    function onOutput(len) {
      this._stats.obytes += len;
    }
  
    conn.on('input', onInput.bind(this));
    conn.on('output', onOutput.bind(this));
  
    this._conn.push(conn);
  
    // pubsub needs to know the client index
    // to be able to quickly find client subscribers
    conn.client.index = this._conn.length - 1;
  }