code: def setUp(self):
      self.N = 1 << 20
      values = [i for i in range(self.N)]
      keys = [i for i in range(2)]
      import itertools
  
      self.data = [value for value in itertools.product(keys, values)]
      self.agg = Aggregator(
          lambda x: [x],
          lambda x, y: x.append(y) or x,
          lambda x, y: x.extend(y) or x,
      )
  
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 1 for calling the ExternalGroupByTests obj's underlying member method code with example usage: obj.setUp() without return types