A line-oriented non-ascii byte finder, with unnecessary elegance

non-ascii.py

import sys
from typing import Iterator, Optional

ascii_range = range(32, 128)

def is_non_ascii(b):
    return b not in ascii_range

def non_ascii_iter(bs):
    return (b for b in bs if is_non_ascii(b))

def first_non_ascii_byte(bs):
    return next(non_ascii_iter(bs), None)

def contains_non_ascii(bs):
    return first_non_ascii_byte(bs) is not None

if __name__ == '__main__':
    if len(sys.argv) != 2:
        program = sys.argv[0]
        print(f'usage: python {program} PATH')
        sys.exit(1)

    path = sys.argv[1]

    with open(path, mode='rb') as f:
        for (line_index, line) in enumerate(f):
            line_without_lf = line.rstrip(b'\n')
            if contains_non_ascii(line_without_lf):
                line_number = line_index + 1
                line_representaion = repr(line_without_lf)
                line_representaion_without_quotes = line_representaion[2:-1]
                print(f'{path}:{line_number}: {line_representaion_without_quotes}')