Generator to yield items from a series of sorted iterables in merged order.

mergeiter.py

import operator

def mergeiter(*iterables):
    """Given a set of sorted iterables, yield the next value in merged order"""
    iterables = [iter(it) for it in iterables]
    iterables = {i: [next(it), i, it] for i, it in enumerate(iterables)}
    while True:
        value, i, it = min(iterables.values(), key=operator.itemgetter(0))
        yield value
        try:
            iterables[i][0] = next(it)
        except StopIteration:
            del iterables[i]
            if not iterables:
                raise