code: def test_groupby_column_index_name_lost_fill_funcs(func):
      # GH: 29764 groupby loses index sometimes
      df = DataFrame(
          [[1, 1.0, -1.0], [1, np.nan, np.nan], [1, 2.0, -2.0]],
          columns=Index(["type", "a", "b"], name="idx"),
      )
      df_grouped = df.groupby(["type"])[["a", "b"]]
      result = getattr(df_grouped, func)().columns
      expected = Index(["a", "b"], name="idx")
      tm.assert_index_equal(result, expected)
  
file_path: pandas/pandas/tests/groupby/test_missing.py
imports: import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, date_range
  import pandas._testing
label_desc: Use image node_id 1 for calling a global function with example usage: test_groupby_column_index_name_lost_fill_funcs(func) without return types