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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 _list_and_update(self):
 """ Update current list of resources by doing a full fetch. Overwrites all current resource info. """

        initial_resources = getattr(self.api, self.list_method_name)(
            self.namespace,
            label_selector=self.label_selector,
            field_selector=self.field_selector,
            _request_timeout=self.request_timeout,
        )
        # This is an atomic operation on the dictionary!
        self.resources = {p.metadata.name: p for p in initial_resources.items}
        # return the resource version so we can hook up a watch
        return initial_resources.metadata.resource_version