code: def test_dropna(self, closed):
      expected = IntervalIndex.from_tuples(
          [(0.0, 1.0), (1.0, 2.0)], closed=closed
      )
  
      ii = IntervalIndex.from_tuples(
          [(0, 1), (1, 2), np.nan], closed=closed
      )
      result = ii.dropna()
      tm.assert_index_equal(result, expected)
  
      ii = IntervalIndex.from_arrays(
          [0, 1, np.nan], [1, 2, np.nan], closed=closed
      )
      result = ii.dropna()
      tm.assert_index_equal(result, expected)
  
imports: from itertools import permutations
  import re
  import numpy
  import pytest
  import pandas
  from pandas import Index, Interval, IntervalIndex, Timedelta, Timestamp, date_range, interval_range, isna, notna, timedelta_range
  import pandas._testing
  import pandas.core.common
label_desc: Use image node_id 19 for calling the TestIntervalIndex obj's underlying member method code with example usage: obj.test_dropna(closed) without return types