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: main.go
    path of file: ./repos/quic-go/interop/client
    
    the code of the file until where you have to start completion: package main

import (
	"crypto/tls"
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"strings"
	"time"

	"golang.org/x/sync/errgroup"

	"github.com/quic-go/quic-go"
	"github.com/quic-go/quic-go/http3"
	"github.com/quic-go/quic-go/internal/handshake"
	"github.com/quic-go/quic-go/internal/protocol"
	"github.com/quic-go/quic-go/internal/qtls"
	"github.com/quic-go/quic-go/interop/http09"
	"git
    
func downloadFile(cl http.RoundTripper, url string, use0RTT bool) error {
	method := http.MethodGet
	if use0RTT {
		method = http09.MethodGet0RTT
	}
	req, err := http.NewRequest(method, url, nil)
	if err != nil {
		return err
	}
	rsp, err := cl.RoundTrip(req)
	if err != nil {
		return err
	}
	defer rsp.Body.Close()

	file, err := os.Create("/downloads" + req.URL.Path)
	if err != nil {
		return err
	}
	defer file.Close()
	_, err = io.Copy(file, rsp.Body)
	return err
}