import functools

def _rejoin_slice_words(method_name, source, wordslice, sep=None, limit=None, joiner=None):

    if joiner is None:

        joiner = ' ' if sep is None else sep

    return joiner.join(_slice_words(method_name, source, wordslice, sep, limit))

rejoin_slice_words = functools.partial(_rejoin_slice_words, 'split')

rejoin_rslice_words = functools.partial(_rejoin_slice_words, 'rsplit')

def _slice_words(method_name, source, wordslice, sep=None, limit=None):

    return getattr(source, method_name)(sep, limit)[wordslice]

slice_words = functools.partial(_slice_words, 'split')

rslice_words = functools.partial(_slice_words, 'rsplit')