code: def test_ngroup_descending(self):
      df = DataFrame(["a", "a", "b", "a", "b"], columns=["A"])
      g = df.groupby(["A"])
  
      ascending = Series([0, 0, 1, 0, 1])
      descending = Series([1, 1, 0, 1, 0])
  
      tm.assert_series_equal(descending, (g.ngroups - 1) - ascending)
      tm.assert_series_equal(ascending, g.ngroup(ascending=True))
      tm.assert_series_equal(descending, g.ngroup(ascending=False))
  
imports: from itertools import product
  from string import ascii_lowercase
  import numpy
  import pytest
  from pandas import DataFrame, Index, MultiIndex, Period, Series, Timedelta, Timestamp, date_range
  import pandas._testing
label_desc: Use image node_id 14 for calling the TestCounting obj's underlying member method code with example usage: obj.test_ngroup_descending() without return types