def METHOD_NAME(iterable: Iterable) -> Iterable:
    """Preprimes an iterator so the first value is calculated immediately
    but not returned until the first iteration
    """
    itr = iter(iterable)
    try:
        first = next(itr)  # itr.next() in Python 2
    except StopIteration:
        return itr
    return itertools.chain([first], itr)