def leaf_node_changed(conf, path):
    """
    Check if a leaf node was altered. If it has been altered - values has been
    changed, or it was added/removed, we will return a list containing the old
    value(s). If nothing has been changed, None is returned.
    NOTE: path must use the real CLI node name (e.g. with a hyphen!)
    """
    from vyos.configdiff import get_config_diff
    D = get_config_diff(conf, key_mangling=('-', '_'))
    D.set_level(conf.get_level())
    (new, old) = D.get_value_diff(path)

    # if node is valueLess, on change old or new (depending on addition or deletion) will be {} and is treated as None

    if new != old:
        if old is None:
            return []
        if isinstance(old, str):
            return [old]
        if isinstance(old, list):
            if isinstance(new, str):
                new = [new]
            elif isinstance(new, type(None)):
                new = []
            return list_diff(old, new)
    return None