code: def test_flatmap(self):
      data = [(1, 11), (2, 12)]
      dist_data = PrivateRDDTest.sc.parallelize(data)
      budget_accountant = budget_accounting.NaiveBudgetAccountant(
          1, 1e-10
      )
  
      def privacy_id_extractor(x):
          return x[0]
  
      prdd = private_spark.PrivateRDD(
          dist_data, budget_accountant, privacy_id_extractor
      )
  
      result = prdd.flat_map(
          lambda x: [(x[0], x[1] * 2), (x[0], x[1] * 2 + 1)]
      )
  
      self.assertEqual(
          result._rdd.collect(),
          [(1, (1, 22)), (1, (1, 23)), (2, (2, 24)), (2, (2, 25))],
      )
      self.assertEqual(
          result._budget_accountant, prdd._budget_accountant
      )
  
imports: import pyspark
  from pyspark import SparkContext
  from absl.testing import parameterized
  from unittest.mock import patch
  import unittest
  import sys
  import collections
  import pipeline_dp
  from pipeline_dp import aggregate_params
  from pipeline_dp import budget_accounting, private_spark
label_desc: Use image node_id 5 for calling the PrivateRDDTest obj's underlying member method code with example usage: obj.test_flatmap() and returns: x