what is the correct method call for checking if a message is pinned or not in telethon 1.36?

i searched a lot, i read docs but it confuses me.

Here’s the snippet:

    if command_name == 'unpin':
        message = event.message
        if not message.is_reply:
            await event.reply("Please reply to a pinned message to unpin it! Usage: /unpin <reply>")
            return

        try:
            chat = await event.get_input_chat()
            replied_message = await message.get_reply_message()
            pinned_messages = await client.get_pinned_messages(chat)
            is_pinned = any(msg.id == replied_message for msg in pinned_messages)

            if is_pinned:
                await client.unpin_message(chat, replied_message)
                await event.reply("unpinned message from group")
            else:
                await event.reply("can't unpin, maybe bot don't have required permission or another errors occurred.")

        except ValueError:
            await event.reply("An error occurred.")
        except Exception as e:
            await event.reply(f"Error pinning message: {str(e)}")

i tried pinned_messages = await client.get_pinned_messages(chat) and got this: 'TelegramClient' object has no attribute 'get_pinned_messages'