Flask - send a bytes downloadable file

So I know you can use flask's send_file method that you choose a path on your computer but in my case, I need to read the file as bytes(because I am sending the file from a different python-client) So I have to send it as bytes and then the server would receive it. but I need to make it so some URL will download you this file can I just return the bytes and it will automatically download the file? so something like this:

f = b""
with open("/somefile.txt", "rb") as some_file:
    f = some_file.read()

return f # and make this download the file that I read

Below is an example adjusted from: https://flask.palletsprojects.com/en/stable/patterns/streaming/

You need a generator function which yields the data,
and then to call that function from the Response object.

from flask import Response 

@app.route("/")
def index():
    def generate():
        with open('somefile.txt','rb') as f:
            for row in f:
                yield row 
    return Response(generate(), mimetype='text/csv')

Then when you visit this route in the browser, you're immediately prompted to download the streaming data.