merge multi generator

merge.py

import heapq

def merge(*args):
    h = []
    for g in args:
        try:
            a = g.next()
        except StopIteration:
            continue
        heapq.heappush(h, (a, g))
    while h:
        elem = heapq.heappop(h)
        yield elem[0]
        g = elem[1]
        try:
            a = g.next()
        except StopIteration:
            continue
        heapq.heappush(h, (a, g))