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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 new_relic_stats(self):
 """ Get stats for this instance. """

        if self._new_relic_stats is None:
            # if this is a sharded instance, fetch shard stats in parallel
            if self.type == 'mongodb_sharded':
                shards = [Shard(self.name, self._service_url + 'shards/',
                                self._client, shard_doc)
                          for shard_doc in self.shards().get('data')]
                fs = []
                with futures.ThreadPoolExecutor(len(shards)) as executor:
                    for shard in shards:
                        fs.append(executor.submit(shard.get_shard_stats))
                    futures.wait(fs, timeout=None, return_when=futures.ALL_COMPLETED)
                stats_this_second = self._rollup_shard_stats_to_instance_stats(
                    {shard.name: future.result() for (shard, future) in zip(shards, fs)})
                # power nap
                time.sleep(1)
                # fetch again
                fs = []
                with futures.ThreadPoolExecutor(len(shards)) as executor:
                    for shard in shards:
                        fs.append(executor.submit(shard.get_shard_stats))
                    futures.wait(fs, timeout=None, return_when=futures.ALL_COMPLETED)
                stats_next_second = self._rollup_shard_stats_to_instance_stats(
                    {shard.name: future.result() for (shard, future) in zip(shards, fs)})
                self._new_relic_stats = self._compile_new_relic_stats(stats_this_second, stats_next_second)
            else:
                # fetch stats like we did before (by hitting new_relic_stats API resource)
                response = requests.get('{}{}'.format(self._url,
                                        'new-relic-stats'),
                                        **self._instances._default_request_kwargs)
                self._new_relic_stats = json.loads(response.content).get(
                    'data') if response.status_code == 200 else {}
        return self._new_relic_stats