code: function Logger(level) {
      if (_.isString(level) && _.has(LogLevel, level)) {
          this.level = LogLevel[level];    
      } else if (_.isNumber(level) && level >= 0 && level <= 4) {
          this.level = level;
      } else {
          this.level = LogLevel.info;
      }    
  }
docs: Logger that logs exclusively to stderr so that logging doesn't pollute the
  scraper result which is written to stdout.