def METHOD_NAME(old, new):
    '''
    Returns the difference between the old and new strings when split on
    whitespace. Considers punctuation a part of the word
    This function is intended as an example; you'll probably want
    a more sophisticated wrapper in practice.
    Params:
        old     the old string
        new     the new string
    Returns:
        the output of `diff` on the two strings after splitting them
        on whitespace (a list of change instructions; see the docstring
        of `diff`)
    Examples:
        >>> string_diff('The quick brown fox', 'The fast blue fox')
        ... # doctest: +NORMALIZE_WHITESPACE
        [('=', ['The']),
         ('-', ['quick', 'brown']),
         ('+', ['fast', 'blue']),
         ('=', ['fox'])]
    '''
    return diff(old.split(), new.split())