Creating a sums file from the GitHub workflow

sum_files.py

#!/usr/bin/env python3

import hashlib
import io
import os
import pathlib
import sys

def sum_file(hasher, file_path):

    assert callable(hasher), 'the hasher must be callable'
    hasher = hasher()

    file_path = pathlib.Path(file_path)
    buffer_size = io.DEFAULT_BUFFER_SIZE
    with file_path.open('rb') as f:
        data = f.read(buffer_size)
        while len(data) > 0:
            hasher.update(data)
            data = f.read(buffer_size)

    return hasher.hexdigest()

def main(args):

    sum_type = args[1]
    if sum_type not in hashlib.algorithms_available:
        raise ValueError('the hash algorithm is not available')

    func = getattr(hashlib, sum_type)
    assert callable(func), 'the sum_type attribute was not callable'

    for arg in args[2:]:
        path = pathlib.Path(arg)
        if path.is_file():
            file = path.resolve(strict=True)
            digest = sum_file(func, file)
            line = f'{digest} *{file.name}'
            print(line, flush=True)

if '__main__' == __name__:
    main(sys.argv)