grep.py

import re
class Grep:
    def __init__(self, pattern):
        self.pattern = re.compile(pattern)

    def __ror__(self, iterable):
        for x in iterable:
            if self.pattern.match(x):
                yield x
class Wc:
    def __init__(self, t):
        self.count = 0
        if t == '-l':
            self.type = 'l'
        elif t == '-c':
            self.type = 'c'
        else:
            raise ValueError()
    def __ror__(self, iterable):
        for x in iterable:
            if self.type == 'l':
                self.count += 1
            elif self.type == 'c':
                self.count += len(x)
        return self.count
   
open('/home/mykola/test.txt') | Grep('abc') | Wc('-c')
open('/home/mykola/test.txt') | Grep('abc') | Wc('-l')