code: function RedisClient(opts) {
    opts = opts || {};
    BaseClient.apply(this, arguments);
    this.recordsToKeep = opts.recordsToKeep || 1000;
    this.namespace = opts.namespace || 'stats';
    this.client = opts.redisClient;
  }
docs: A client that can send metrics data to a redis backend
  @param {Object} opts
  @param {Object} opts.redisClient an instance of the redis nodejs client.
  @param {Number} opts.recordsToKeep the number of records to keep for each metric. Default is 1000.
  @param {String} opts.namespace name space for each metric key. It will be used to prefix each metric key followed by ':'. Default is `stats`. So each metric key will be like `stats:<metric key>`.