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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 refresh(self):
 """ Reload list of bundles from the store :return: self """

        self._bundles = {}

        bundles = self._api.get_bundles(self._document.id)
        for bundle in bundles:
            self._bundles[bundle['identifier']] = Bundle(self._api, self._document, bundle)
        
        return self