'_split(text : string) -> [string]
Split the text to wrap into indivisible chunks.  Chunks are
not quite the same as words; see _wrap_chunks() for full
details.  As an example, the text
Look, goof-ball -- use the -b option!
breaks into the following chunks:
\'Look,\', \' \', \'goof-\', \'ball\', \' \', \'--\', \' \',
\'use\', \' \', \'the\', \' \', \'-b\', \' \', \'option!\'
if break_on_hyphens is True, or in:
\'Look,\', \' \', \'goof-ball\', \' \', \'--\', \' \',
\'use\', \' \', \'the\', \' \', \'-b\', \' \', option!\'
otherwise.'

def _split(self, text):

    if isinstance(text, ustr):
        if self.break_on_hyphens:
            pat = self.wordsep_re_uni
        else:
            pat = self.wordsep_simple_re_uni
    elif self.break_on_hyphens:
        pat = self.wordsep_re
    else:
        pat = self.wordsep_simple_re
    chunks = pat.split(text)
    chunks = list(filter(None, chunks))
    return chunks
