code: def test_head_tail_dropna_false():
      # GH#45089
      df = DataFrame(
          [["a", "z"], ["b", np.nan], ["c", np.nan]], columns=["X", "Y"]
      )
      expected = DataFrame(
          [["a", "z"], ["b", np.nan], ["c", np.nan]], columns=["X", "Y"]
      )
  
      result = df.groupby(["X", "Y"], dropna=False).head(n=1)
      tm.assert_frame_equal(result, expected)
  
      result = df.groupby(["X", "Y"], dropna=False).tail(n=1)
      tm.assert_frame_equal(result, expected)
  
      result = df.groupby(["X", "Y"], dropna=False).nth(n=0)
      tm.assert_frame_equal(result, expected)
  
imports: import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Index, MultiIndex, Series, Timestamp, isna
  import pandas._testing
label_desc: Use image node_id 40 for calling a global function with example usage: test_head_tail_dropna_false() without return types