[cmdlineluser]

Perhaps a `DictWriter` would simplify things:

    import csv
    import sys
    
    filename = "example.csv"
    sort_by = "index"
    reverse = True
    
    with open(filename, newline="") as f:
        reader = csv.DictReader(f)
        writer = csv.DictWriter(sys.stdout, fieldnames=reader.fieldnames)
        writer.writeheader()
        writer.writerows(sorted(reader, key=lambda row: int(row[sort_by]), reverse=reverse))

[gabrielsroka]

I thought about that but 1) it seemed like cheating to write to standard out, 2) you're assuming that the column to sort by is an integer whereas I broke that code up a little bit.

But yours has the advantage of being able to support more complex CSVs.