human
Complete this python program:
def key_id_or_name_as_string_n(index):
assistant
#Here is the Python program you requested.

    """Pull out the nth (0-based) key id or name from a key which has parents.
    If a key is present, return its id or name as a string.
    Note that this loses the distinction between integer IDs and strings
    which happen to look like integers. Use key_type to distinguish them.
    This is a useful complement to create_deep_key.
    Args:
    index: The depth of the id or name to extract. Zero is the root key.
    Negative one is the leaf key.
    Returns:
    Function extracting the name or ID of the key at depth index, as a unicode
    string. Returns \\ if key is empty (unsaved), otherwise raises IndexError
    if the key is not as deep as described.
    """
    def transform_function(key):
        id_or_name = _key_id_or_name_n(key, index)
        if (not id_or_name):
            return u''
        return unicode(id_or_name)
    return transform_function