docs: function Janitor (config) {
    this.config = _.defaults(config || {}, {
      concurrency: 2
    });
  
    if (this.config.clientConfig) {
      this.cwlClient = new AWS.CloudWatchLogs(this.config.clientConfig);
    }
    else {
      this.cwlClient = new AWS.CloudWatchLogs();
    }
  
    // Default maximum.
    this.describeLogGroupsLimit = 50;
  }