code: def test_nth_after_selection(selection, dropna):
      # GH#11038, GH#53518
      df = DataFrame(
          {
              "a": [1, 1, 2],
              "b": [np.nan, 3, 4],
              "c": [5, 6, 7],
          }
      )
      gb = df.groupby("a")[selection]
      result = gb.nth(0, dropna=dropna)
      if dropna == "any" or (
          dropna == "all" and selection != ["b", "c"]
      ):
          locs = [1, 2]
      else:
          locs = [0, 2]
      expected = df.loc[locs, selection]
      tm.assert_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 41 for calling a global function with example usage: test_nth_after_selection(selection, dropna) without return types