Stat filesize of files.

    Args:
        images: stream of marv image files

    Returns:
        Stream of filesizes

def filesizes(images):
    """Stat filesize of files.

    Args:
        images: stream of marv image files

    Returns:
        Stream of filesizes
    """
    # Pull each image and push its filesize
    while True:
        img = yield marv.pull(images)
        if img is None:
            break
        yield marv.push(img.size)