code: def privacy_id_extractor(x):
      return f"pid:{x}"
  
imports: import unittest
  import apache_beam
  from apache_beam.runners.portability import fn_api_runner
  from apache_beam import pvalue
  from unittest.mock import patch
  import apache_beam.testing.util
  from apache_beam.testing.test_pipeline import TestPipeline
  import pipeline_dp
  from pipeline_dp import private_beam
  from pipeline_dp import aggregate_params, budget_accounting
label_desc: Use image node_id 1 for calling the PrivateBeamTest obj's underlying member method code with example usage: obj.privacy_id_extractor(x) and returns: str, x