You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: config.go
    path of file: ./repos/aws-sdk-go-v2/feature/s3/manager/internal/integration/downloader
    
    the code of the file until where you have to start completion: //go:build integration && perftest
// +build integration,perftest

package downloader

import (
	"flag"
	"net/http"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go-v2/feature
    
func (c *SDKConfig) SetupFlags(prefix string, flagset *flag.FlagSet) {
	prefix += "sdk."

	flagset.Int64Var(&c.PartSize, prefix+"part-size", manager.DefaultDownloadPartSize,
		"Specifies the `size` of parts of the object to download.")
	flagset.IntVar(&c.Concurrency, prefix+"concurrency", manager.DefaultDownloadConcurrency,
		"Specifies the number of parts to download `at once`.")
}