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: material.go
    path of file: ./repos/wechat/officialaccount/material
    
    the code of the file until where you have to start completion: package material

import (
	"encoding/json"
	"errors"
	"fmt"

	"github.com/silenceper/wechat/v2/officialaccount/context"
	"github.com/silenceper/wechat/v2/util"
)

const (
	addNewsURL          = "https://api.wei
    
func (material *Material) BatchGetMaterial(permanentMaterialType PermanentMaterialType, offset, count int64) (list ArticleList, err error) {
	var accessToken string
	accessToken, err = material.GetAccessToken()
	if err != nil {
		return
	}
	uri := fmt.Sprintf("%s?access_token=%s", batchGetMaterialURL, accessToken)

	req := reqBatchGetMaterial{
		Type:   permanentMaterialType,
		Offset: offset,
		Count:  count,
	}

	var response []byte
	response, err = util.PostJSON(uri, req)
	if err != nil {
		return
	}

	err = util.DecodeWithError(response, &list, "BatchGetMaterial")
	return
}