使用BeautifulSoup从python中提取XML中的特定标记

我有一个元数据文件,如下所示:

<?xml version='1.0' encoding='utf-8'?>
<package xmlns="http://www.idpf.org/2007/opf" unique-identifier="uuid_id" version="2.0">
    <metadata xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:opf="http://www.idpf.org/2007/opf">
        <dc:title>Princeton Review Digital SAT Premium Prep, 2024: 4 Practice Tests + Online Flashcards + Review &amp; Tools</dc:title>
        <dc:creator opf:file-as="Princeton Review, The" opf:role="aut">The Princeton Review</dc:creator>
        <dc:identifier opf:scheme="ISBN">9780593516874</dc:identifier>
        <dc:identifier opf:scheme="AMAZON">0593516877</dc:identifier>
        <dc:identifier opf:scheme="GOODREADS">63139948</dc:identifier>
        <dc:identifier opf:scheme="GOOGLE">o6i4EAAAQBAJ</dc:identifier>
    </metadata>
</package>

我知道如何使用BeautifulSoup提取以下字段 <dc.title> .我很难只提取ISBN字段( <dc:identifier opf:scheme="ISBN"> )。

from bs4 import BeautifulSoup

with open ('metadata.opf', 'r') as f:
    file = f.read()

metadata = BeautifulSoup(file, 'xml')
title = metadata.find('dc:title')
print(title.text)

author = metadata.find('dc:creator')
print(author.text)

# isbn = metadata.find_all('dc:identifier'). # This finds 4 fields, as expected.  

我该如何限制它?我不能依赖于字段的顺序,ISBN的长度也可能不同。