hashcomfort.py

import hashlib 

def sha256fromfile(filename: str) -> str:
    sha  = hashlib.sha256()
    b  = bytearray(128*1024)
    mv = memoryview(b)
    with open(filename, 'rb', buffering=0) as f:
        for n in iter(lambda : f.readinto(mv), 0):
            sha.update(mv[:n])
    return sha.hexdigest()