code: function _logger(str, level) {
      /* eslint-disable no-console */
      console.log(level.toUpperCase() + " pool " + this._opts.name + " - " + str);
      /* eslint-enable no-console */
  }
docs: ---------------------------------------------------------------------------------------------- // 
  Default logging method, just logs to `console.log`.
  
  @private
  @memberof PromisePool
  
  @param {string} str      - The message to log.
  @param {string} level    - The logging priority/level.
  
  @return {undefined}