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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 _to_url(self):
 """ Serialises this query into a request-able URL including parameters """

        url = self._target_url

        params = collections.defaultdict(list, copy.deepcopy(self._filters))
        if self._order_by is not None:
            params['sort'] = self._order_by
        for k, vl in self._extra.items():
            params[k] += vl

        if params:
            url += "?" + urllib.parse.urlencode(params, doseq=True)

        return url