code: def test_2_group_by(self):
      builder = dataframes.QueryBuilder(get_pandas_df(), "privacy_key")
      builder.groupby(
          "group_key",
          max_groups_contributed=1,
          max_contributions_per_group=1,
      )
      with self.assertRaisesRegex(
          ValueError, "groupby can be called only once"
      ):
          builder.groupby(
              "group_key",
              max_groups_contributed=1,
              max_contributions_per_group=1,
          )
  
imports: from absl.testing import absltest
  from absl.testing import parameterized
  from collections import namedtuple
  import pandas
  from pyspark import sql
  from unittest import mock
  from unittest.mock import patch
  from pipeline_dp import dataframes
  import pipeline_dp
label_desc: Use image node_id 5 for calling the QueryBuilderTest obj's underlying member method code with example usage: obj.test_2_group_by() without return types