def lowercase_ext(filename):
    """
    This is a helper used by UploadSet.save to provide lowercase extensions for
    all processed files, to compare with configured extensions in the same
    case.

    .. versionchanged:: 0.1.4
       Filenames without extensions are no longer lowercased, only the
       extension is returned in lowercase, if an extension exists.

    :param filename: The filename to ensure has a lowercase extension.
    """
    if '.' in filename:
        main, ext = os.path.splitext(filename)
        return main + ext.lower()
    # For consistency with os.path.splitext,
    # do not treat a filename without an extension as an extension.
    # That is, do not return filename.lower().
    return filename
dataset/ETHPy150Open jeffwidman/flask-uploads/flask_uploads.py/lowercase_ext/original