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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 cache_data(self, request, data, key='params'):
 """ Cache data in the session store. :param request: :attr:`django.http.HttpRequest` :param data: Arbitrary data to store. :param key: `str` The key under which to store the data. """

        request.session['%s:%s' % (constants.SESSION_KEY, key)] = data