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: util.go
    path of file: ./repos/alist/drivers/aliyundrive
    
    the code of the file until where you have to start completion: package aliyundrive

import (
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"fmt"
	"net/http"

	"github.com/alist-org/alist/v3/drivers/base"
	"github.com/alist-org/alist/v3/internal/op"
	
    
func (d *AliDrive) getFiles(fileId string) ([]File, error) {
	marker := "first"
	res := make([]File, 0)
	for marker != "" {
		if marker == "first" {
			marker = ""
		}
		var resp Files
		data := base.Json{
			"drive_id":                d.DriveId,
			"fields":                  "*",
			"image_thumbnail_process": "image/resize,w_400/format,jpeg",
			"image_url_process":       "image/resize,w_1920/format,jpeg",
			"limit":                   200,
			"marker":                  marker,
			"order_by":                d.OrderBy,
			"order_direction":         d.OrderDirection,
			"parent_file_id":          fileId,
			"video_thumbnail_process": "video/snapshot,t_0,f_jpg,ar_auto,w_300",
			"url_expire_sec":          14400,
		}
		_, err, _ := d.request("https://api.alipan.com/v2/file/list", http.MethodPost, func(req *resty.Request) {
			req.SetBody(data)
		}, &resp)

		if err != nil {
			return nil, err
		}
		marker = resp.NextMarker
		res = append(res, resp.Items...)
	}
	return res, nil
}