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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _html(self, text):
        '''Parse a Tweet and generate HTML.'''
        html = URL_REGEX.sub(self._parse_urls, text)
        html = USERNAME_REGEX.sub(self._parse_users, html)
        html = LIST_REGEX.sub(self._parse_lists, html)
        return HASHTAG_REGEX.sub(self._parse_tags, html)