docs: function PoolCluster(config) {
    EventEmitter.call(this);
  
    config = config || {};
    this._canRetry = typeof config.canRetry === 'undefined' ? true : config.canRetry;
    this._defaultSelector = config.defaultSelector || 'RR';
    this._removeNodeErrorCount = config.removeNodeErrorCount || 5;
    this._restoreNodeTimeout = config.restoreNodeTimeout || 0;
  
    this._closed = false;
    this._findCaches = Object.create(null);
    this._lastId = 0;
    this._namespaces = Object.create(null);
    this._nodes = Object.create(null);
  }