Prepend the BOM to indicate a file is UTF-8

add-the-utf8-mark.py

import codecs
import sys

def prepend_bom(filename):
    with open( filename, 'r+b' ) as csv:
        existing = csv.read()
        if b'\xef\xbb\xbf' == existing[0:3]:
            print("Byte-order mark already present: leaving file as-is.")
            return

        print("Adding byte-order mark to beginning of file to indicate that it's a UTF-8 file.")
        csv.seek(0)
        csv.write(codecs.BOM_UTF8)
        csv.write(existing)

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print(f"Supply a filename: python3 {sys.argv[0]} survey-results.csv")
        sys.exit(1)

    filename = sys.argv[1]

    prepend_bom(filename)