code: def test_small_dataset(self):
      m = ExternalMerger(self.agg, 1000)
      m.mergeValues(self.data)
      self.assertEqual(m.spills, 0)
      self.assertEqual(
          sum(sum(v) for k, v in m.items()), sum(range(self.N))
      )
  
      m = ExternalMerger(self.agg, 1000)
      m.mergeCombiners(
          map(lambda x_y1: (x_y1[0], [x_y1[1]]), self.data)
      )
      self.assertEqual(m.spills, 0)
      self.assertEqual(
          sum(sum(v) for k, v in m.items()), sum(range(self.N))
      )
  
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 2 for calling the MergerTests obj's underlying member method code with example usage: obj.test_small_dataset() without return types