code: def test_groupby():
      df = pd.DataFrame(
          {
              "a": [3, 4, 5, 3, 5, 4, 1, 2, 3],
              "b": [1, 3, 4, 5, 6, 5, 4, 4, 4],
          }
      )
      mdf = md.DataFrame(df, chunk_size=2)
      with pytest.raises(KeyError):
          mdf.groupby("c2")
      with pytest.raises(KeyError):
          mdf.groupby(["b", "c2"])
  
      grouped = mdf.groupby("b")
      assert isinstance(grouped, DataFrameGroupBy)
      assert isinstance(grouped.op, DataFrameGroupByOperand)
      assert list(grouped.key_dtypes.index) == ["b"]
  
      grouped = tile(grouped)
      assert len(grouped.chunks) == 5
      for chunk in grouped.chunks:
          assert isinstance(chunk.op, DataFrameGroupByOperand)
  
      series = pd.Series([3, 4, 5, 3, 5, 4, 1, 2, 3])
      ms = md.Series(series, chunk_size=3)
      grouped = ms.groupby(lambda x: x + 1)
  
      assert isinstance(grouped, SeriesGroupBy)
      assert isinstance(grouped.op, DataFrameGroupByOperand)
  
      grouped = tile(grouped)
      assert len(grouped.chunks) == 3
      for chunk in grouped.chunks:
          assert isinstance(chunk.op, DataFrameGroupByOperand)
  
      with pytest.raises(TypeError):
          ms.groupby(lambda x: x + 1, as_index=False)
  
imports: from collections import OrderedDict
  import numpy
  import pandas
  import pytest
  from ..sort import DataFrameGroupbySortShuffle
  from ....None import dataframe
  from ....None import opcodes
  from ....config import option_context
  from ....core import OutputType, tile
  from ....core.operand import OperandStage
  from ...core import DataFrameGroupBy, SeriesGroupBy, DataFrame
  from ..core import DataFrameGroupByOperand, DataFrameShuffleProxy
  from ..aggregation import DataFrameGroupByAgg
  from ..getitem import GroupByIndex
label_desc: Use image node_id 1 for calling a global function with example usage: test_groupby() without return types