ly_n('abcd', 6, too_short=too_short)
        >>> list(it)  # doctest: +IGNORE_EXCEPTION_DETAIL
        Traceback (most recent call last):
        ...
        RuntimeError

        >>> def too_long(item_count):
        ...     print('The boss is going to hear about this')
        >>> it = strictly_n('abcdef', 4, too_long=too_long)
        >>> list(it)
        The boss is going to hear about this
        ['a', 'b', 'c', 'd']

    Nc