如何通过Flask和pymessenger向FB messenger发送输入气泡？

from flask import Flask, request
from pymessenger import Bot

app = Flask(__name__)
bot = Bot("YOUR_PAGE_ACCESS_TOKEN")

@app.route("/", methods=['GET', 'POST'])
def receive_message():
    if request.method == 'GET':
        # 处理验证请求
        verify_token = request.args.get("hub.verify_token")
        challenge = request.args.get("hub.challenge")
        if verify_token == "YOUR_VERIFY_TOKEN":
            return str(challenge)
        else:
            return "Invalid verification token"
    else:
        # 处理接收到的消息
        data = request.get_json()
        if data["object"] == "page":
            for entry in data["entry"]:
                for messaging_event in entry["messaging"]:
                    if messaging_event.get("message"):
                        sender_id = messaging_event["sender"]["id"]
                        recipient_id = messaging_event["recipient"]["id"]
                        message_text = messaging_event["message"]["text"]
                        # 在这里处理消息并发送回复
                        send_message(sender_id, "回复消息内容")
        return "Message Processed"

def send_message(recipient_id, message_text):
    bot.send_text_message(recipient_id, message_text)

if __name__ == "__main__":
    app.run()