code: def test_huge_dataset(self):
      m = ExternalMerger(self.agg, 5, partitions=3)
      m.mergeCombiners(
          map(lambda k_v: (k_v[0], [str(k_v[1])]), self.data * 10)
      )
      self.assertTrue(m.spills >= 1)
      self.assertEqual(sum(len(v) for k, v in m.items()), self.N * 10)
      m._cleanup()
  
imports: import random
  import unittest
  import tempfile
  import os
  from py4j.protocol import Py4JJavaError
  from pyspark import shuffle, CPickleSerializer, SparkConf, SparkContext
  from pyspark.shuffle import Aggregator, ExternalMerger, ExternalSorter, SimpleAggregator, Merger, ExternalGroupBy
label_desc: Use image node_id 7 for calling the MergerTests obj's underlying member method code with example usage: obj.test_huge_dataset() without return types