def iterate(iterator, n):
    """
    Returns the nth element returned by the iterator if there are sufficient elements,
    or None if the iterator has been exhausted.

    :param iterator: The iterator to extract elements from
    :param n: The nth element returned by the iterator will be returned
    :return: An element returned by the iterator
    """
    # throw away n-1 elements
    for index in range(1, n):
        next(iterator, None)

    return next(iterator, None)