code: function create (name, level) {
    name = name || 'karma'
    let logger
    if (loggerCache.hasOwnProperty(name)) {
      logger = loggerCache[name]
    } else {
      logger = log4js.getLogger(name)
      loggerCache[name] = logger
    }
    if (helper.isDefined(level)) {
      logger.setLevel(level)
    }
    return logger
  }
docs: Create a new logger. There are two optional arguments * `name`, which defaults to `karma` and If the `name = 'socket.io'` this will create a special wrapper to be used as a logger for socket.io. * `level`, which defaults to the global level.