Get a Python iterator that tests as false if empty

gistfile1.txt

# This work is dedicated to the public domain or, in any case where copyright may not be relinquished, offered under an MIT License

def _falsey_on_empty(iterable: Iterable[T]) -> Iterable[T]:
    """Return an iterable that is falsey if empty, but always yields the same elements
    
    :returns:
        ``()`` if *iterable* is empty, otherwise an iterable over the same
        values
    
    Iterable values cannot be generally relied on to return ``False`` when
    passed to :func:`bool` if empty.  This function converts empty iterators
    to the empty :class:`tuple`, which does evaluate as false in a Boolean
    context.
    """
    remaining_items = iter(iterable)
    try:
        first = next(remaining_items)
    except StopIteration:
        return ()
    return itertools.chain((first,), remaining_items)