from collections import deque
from itertools import islice, repeat

def consume_deque(n, items):
    deque(islice(items, n), maxlen=0)

def consume_forloop(n, items):
    for _ in islice(items, n):
        pass

def consume_islice(n, items):
    if n == 0:
        return
    next(islice(items, n-1, None), None)

def check(fs):
    for consume in fs:
        items = iter(range(10))
        consume(3, items)
        rest = list(items)
        assert rest == range(3, 10), consume.__name__

if __name__ == "__main__":
    fs = consume_deque, consume_forloop, consume_islice
    check(fs)

    items = repeat(None)

    from timeit import Timer
    for consume in fs:
        print consume.__name__
        for n in (10, 100, 1000):
            print "%6d:" % n,
            print Timer("consume(%s, items)" % n,
                        "from __main__ import consume, items").timeit()
        print