code: func LoggerAddHandler(ctx context.Context, f func(*log.Record) error) context.Context {
  	logger := loggerFromContext(ctx)
  	loggerHandler := log.MultiHandler(logger.handler, log.FuncHandler(f))
  	logger.SetHandler(loggerHandler)
  
  	return context.WithValue(ctx, LoggerKey, logger)
  }
docs: // Add a handler to a logger in the context