studentinfo_code [edited copy - for so_q_74567311]

## for https://stackoverflow.com/q/74567311/6146136
#### links to outputs:
###### studentinfo_output.xml at https://pastebin.com/bPFg8TBL
###### studentinfo_op_unpretty.xml at https://pastebin.com/6NgFsYU0
###### studentinfo_op_regpretty.xml at https://pastebin.com/5FQxLzCC


from bs4 import BeautifulSoup

with open('studentinfo.xml', 'r') as f:
    xhtml = f.read() # [I just don't like "file" as a variable name]
soup = BeautifulSoup(xhtml, 'lxml') ##  'xml' parser ---> lose namespaces

enumTags = ['st:name']
for d in [c for c in soup.descendants if c.name]:
    for name in enumTags:
        for i, t in enumerate(d.find_all(name, recursive=False)):
            t.name = f'{t.name}{i}'

            # print(soup.prettify)
            # prettify is a method so it should be prettify()
            # if you print inside loop, it'll print with every edit

# to save the new xml [3 different options]
with open('studentinfo_output.xml', 'wb') as f:
    f.write(soup.prettify('utf-8')) # option 1
with open('studentinfo_op_unpretty.xml', 'wb') as f:
    f.write(str(soup).encode('utf-8')) # option 2

import re
rpx = re.sub('[^> ]\s*\n\s*<', '<', soup.prettify())
rpx = re.sub('>\s*\n\s*[^< ]', '>', rpx)
with open('studentinfo_op_regpretty.xml', 'wb') as f:
    f.write(rpx.encode('utf-8')) # option 3