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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(self, instance_name):
 """Get an ObjectRocket instance by name. :param str instance_name: The name of the instance to retrieve. :returns: A subclass of :py:class:`bases.BaseInstance`, or None if instance does not exist. :rtype: :py:class:`bases.BaseInstance` """

        url = self._url + instance_name + '/'
        response = requests.get(url, **self._default_request_kwargs)
        data = self._get_response_data(response)
        return self._concrete_instance(data)