def delete_files_within_dir(directory: str, filenames: List[str]) -> None:
    """
    Delete files within ``directory`` whose filename *exactly* matches one of
    ``filenames``.
    """
    for dirpath, dirnames, fnames in os.walk(directory):
        for f in fnames:
            if f in filenames:
                fullpath = os.path.join(dirpath, f)
                log.debug("Deleting {!r}", fullpath)
                os.remove(fullpath)