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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 json(self):
 """Returns the json-encoded content of the response, if any."""

        if hasattr(self, '_json'):
            return self._json
        try:
            self._json = json.loads(self.text or self.content)
        except ValueError:
            self._json = None
        return self._json