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: backfill.go
    path of file: ./repos/magic-modules/tools/issue-labeler/labeler
    
    the code of the file until where you have to start completion: package labeler

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"sort"

	"github.com/golang/glog"
)

type ErrorResponse struct {
	Message string
}

type Issue struct {
	Number      uint64
	Body        string
	Labels      []Label
	PullRequest map[string]any `json:"pull_request"`
}

type Label struct {
	Name string
}

type IssueUpdate struct {
	Number    uint64
	Labels    []string
	OldLabels []string
}

type IssueUpdateBody struct {
	Labels []string `json:"labels"`
}

func GetIssues(repository, since string) []Issue {
	client := &ht
    
func GetIssues(repository, since string) []Issue {
	client := &http.Client{}
	done := false
	page := 1
	var issues []Issue
	for !done {
		url := fmt.Sprintf("https://api.github.com/repos/%s/issues?since=%s&per_page=100&page=%d", repository, since, page)
		req, err := http.NewRequest("GET", url, nil)
		if err != nil {
			glog.Exitf("Error creating request: %v", err)
		}
		req.Header.Add("Accept", "application/vnd.github+json")
		req.Header.Add("Authorization", "Bearer "+os.Getenv("GITHUB_TOKEN"))
		req.Header.Add("X-GitHub-Api-Version", "2022-11-28")
		resp, err := client.Do(req)
		if err != nil {
			glog.Exitf("Error listing issues: %v", err)
		}
		defer resp.Body.Close()
		body, err := io.ReadAll(resp.Body)
		if err != nil {
			glog.Exitf("Error reading response body: %v", err)
		}
		var newIssues []Issue
		json.Unmarshal(body, &newIssues)
		if len(newIssues) == 0 {
			var err ErrorResponse
			json.Unmarshal(body, &err)
			if err.Message == "Bad credentials" {
				glog.Exitf("Error from API: Bad credentials")
			}
			glog.Infof("API returned message: %s", err.Message)
			done = true
		} else {
			issues = append(issues, newIssues...)
			page++
		}
	}
	return issues
}