code: def test_last_valid_index(self):
      pser = pd.Series([250, 1.5, 320, 1, 0.3, None, None, None, None])
      psser = ps.from_pandas(pser)
      self.assert_eq(pser.last_valid_index(), psser.last_valid_index())
  
      # MultiIndex columns
      midx = pd.MultiIndex(
          [["lama", "cow", "falcon"], ["speed", "weight", "length"]],
          [[0, 0, 0, 1, 1, 1, 2, 2, 2], [0, 1, 2, 0, 1, 2, 0, 1, 2]],
      )
      pser.index = midx
      psser = ps.from_pandas(pser)
      self.assert_eq(pser.last_valid_index(), psser.last_valid_index())
  
      # Empty Series
      pser = pd.Series([])
      psser = ps.from_pandas(pser)
      self.assert_eq(pser.last_valid_index(), psser.last_valid_index())
  
imports: import unittest
  import numpy
  import pandas
  from pyspark import pandas
  from pyspark.testing.pandasutils import ComparisonTestBase
  from pyspark.testing.sqlutils import SQLTestUtils
label_desc: Use image node_id 14 for calling the SeriesIndexMixin obj's underlying member method code with example usage: obj.test_last_valid_index() without return types