def _classify_directory_contents(filesystem, root):
    """Classify contents of a directory as files/directories.

    Args:
        filesystem: The fake filesystem used for implementation
        root: (str) Directory to examine.

    Returns:
        (tuple) A tuple consisting of three values: the directory examined,
        a list containing all of the directory entries, and a list
        containing all of the non-directory entries.
        (This is the same format as returned by the `os.walk` generator.)

    Raises:
        Nothing on its own, but be ready to catch exceptions generated by
        underlying mechanisms like `os.listdir`.
    """
    dirs = []
    files = []
    for entry in filesystem.listdir(root):
        if filesystem.isdir(filesystem.joinpaths(root, entry)):
            dirs.append(entry)
        else:
            files.append(entry)
    return root, dirs, files