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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def GetMetricMetadata():
 """Returns a list of MetricMetadata for communicator-related metrics."""

  return [
      stats_utils.CreateCounterMetadata("grr_client_unknown"),
      stats_utils.CreateCounterMetadata("grr_decoding_error"),
      stats_utils.CreateCounterMetadata("grr_decryption_error"),
      stats_utils.CreateCounterMetadata("grr_authenticated_messages"),
      stats_utils.CreateCounterMetadata("grr_unauthenticated_messages"),
      stats_utils.CreateCounterMetadata("grr_rsa_operations"),
      stats_utils.CreateCounterMetadata(
          "grr_encrypted_cipher_cache", fields=[("type", str)]),
  ]