code: def test_frame_groupby(self):
      df = pd.DataFrame(
          {"A": [1, 2, 1, 2], "B": [4, 5, 6, 7], "C": [7, 8, 9, 10]},
          columns=["A", "B", "C"],
      )
      s = pd.Series([1, 2, 3, 4])
  
      mdf = pdml.ModelFrame(df, target=s)
      self.assertIsInstance(mdf, pdml.ModelFrame)
  
      grouped = mdf.groupby("A")
      self.assertIsInstance(
          grouped, pdml.core.groupby.ModelFrameGroupBy
      )
  
      df = grouped.get_group(1)
      self.assertIsInstance(df, pdml.ModelFrame)
  
      expected = pd.Series([1, 3], index=[0, 2], name=".target")
      tm.assert_series_equal(df.target, expected)
      self.assertIsInstance(df.target, pdml.ModelSeries)
  
file_path: pandas-ml/pandas_ml/test/test_groupby.py
imports: import numpy
  import pandas
  import sklearn.datasets
  import pandas_ml
  import pandas_ml.util.testing
label_desc: Use image node_id 1 for calling the TestModelFrameGroupBy obj's underlying member method code with example usage: obj.test_frame_groupby() without return types