wc -l

wc-block-64k.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import sys


def wc_block_64k(name, blocksize=65536):
    def blocks(f):
        while True:
            b = f.read(blocksize)
            if b:
                yield b
            else:
                break

    with open(name, 'r') as f:
        return sum(bl.count('\n') for bl in blocks(f))


print(wc_block_64k(sys.argv[1]))