This function will interleave results from multiple iterators, exhausting all iterators in the process (i.e. ignoring iterators that has no more value).

gistfile1.py

import itertools

def iter_interleave(*args):
    iterators = [(x for x in it) for it in args]
    has_values = [True for _ in xrange(len(iterators))]
    while max(has_values):
        for it, has_value, i in itertools.izip(iterators, has_values, xrange(len(iterators))):
            if has_value:
                try:
                    value = it.next()
                    yield value
                except StopIteration:
                    has_values[i] = False