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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 membership_for(self, username):
 """Retrieve the membership information for the user. :param str username: (required), name of the user :returns: dictionary """

        url = self._build_url('memberships', username, base_url=self._api)
        json = self._json(self._get(url), 200)
        return json or {}