如何在python中向Gmail-API发送批处理请求？

import os
import pickle
import base64
from google.auth.transport.requests import Request
from google_auth_oauthlib.flow import InstalledAppFlow
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError

# 定义要发送的邮件内容
message = {
    'subject': '邮件主题',
    'body': '邮件正文',
    'to': '收件人邮箱地址',
    'from': '发件人邮箱地址'
}

# 定义发送邮件的函数
def send_email(service, message):
    try:
        message = create_message(message['from'], message['to'], message['subject'], message['body'])
        send_message(service, 'me', message)
        print('邮件发送成功！')
    except HttpError as error:
        print(f'邮件发送失败：{error}')

# 创建邮件消息
def create_message(sender, to, subject, message_text):
    message = {
        'from': sender,
        'to': to,
        'subject': subject,
        'text': message_text
    }
    return message

# 发送邮件
def send_message(service, user_id, message):
    try:
        message = (service.users().messages().send(userId=user_id, body=message)
                   .execute())
        return message
    except HttpError as error:
        print(f'发送邮件失败：{error}')

# 加载凭据
def load_credentials():
    creds = None
    if os.path.exists('token.pickle'):
        with open('token.pickle', 'rb') as token:
            creds = pickle.load(token)
    if not creds or not creds.valid:
        if creds and creds.expired and creds.refresh_token:
            creds.refresh(Request())
        else:
            flow = InstalledAppFlow.from_client_secrets_file(
                'credentials.json', ['https://www.googleapis.com/auth/gmail.send'])
            creds = flow.run_local_server(port=0)
        with open('token.pickle', 'wb') as token:
            pickle.dump(creds, token)
    return creds

# 构建Gmail API服务
def build_service():
    creds = load_credentials()
    service = build('gmail', 'v1', credentials=creds)
    return service

# 发送邮件
service = build_service()
send_email(service, message)