我需要從消息中獲取圖片，如果它在那里我使用重寫版本我試過這個：message.attachments[0]['url']但得到一個錯誤    Ignoring exception in on_messageTraceback (most recent call last):  File "C:\Users\vlad0\AppData\Roaming\Python\Python36\site-packages\discord\client.py", line 227, in _run_event    await coro(*args, **kwargs)  File "c:\Users\vlad0\Desktop\bot\bot.py", line 121, in on_message    print(message.attachments[0]['url'])TypeError: 'Attachment' object is not subscriptable如果你只留下索引或只留下附件，你會得到：<discord.message.Attachment object at 0x00000228B8E3BE80>我怎樣才能得到圖片網址？