How to change content of .eml messages in python script where content-maintype is multipart and it's different content types

Question

For several days I'm trying to change content of .eml files in python, specifically I need to exchange hyperlinks. HTTP or HTTPS -> HXXP or HXXPS. I've the biggest problem with content-type of theses messages.

def change_URL_in_EML(eml_path):
    for email in glob.glob(eml_path):
        with open(email, 'rb') as fp:
            msg = BytesParser(policy=policy.default).parse(fp)
            
            if msg.is_multipart():
                for item in msg.get_payload():
            text = get_payload()
                    text.replace('http', 'hxxp')
                    text.replace('https', 'hxxps')
                    msg.set_payload(text)

        with open('My_Path', 'wb') as wp:
            msg = msg.as_bytes() 
            wp.write(msg)

I was trying upper code, and it works on plain messages. I've made my own message with content like:

Hi,

https://eeee.com
http://aaa.com

and it replaces http -> hxxp correctly and make another updated mail. Right now I'm trying to do it with more "extended" emails like newsletter from zalando etc. and I've no idea.