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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 get_url_preview(self, url, ts=None):
 """Get preview for URL. Args: url (str):
 URL to get a preview ts (double):
 The preferred point in time to return a preview for. The server may return a newer version if it does not have the requested version available. """

        params = {'url': url}
        if ts:
            params['ts'] = ts
        return self._send(
            "GET", "",
            query_params=params,
            api_path="/_matrix/media/r0/preview_url"
        )