Creates a new segment.

def create(self, list_id, title, rulegroups):
        """Creates a new segment."""
        body = {
            "Title": title,
            "RuleGroups": rulegroups}
        response = self._post("/segments/%s.json" % list_id, json.dumps(body))
        self.segment_id = json_to_py(response)
        return self.segment_id