code: def test_table_get_index(self):
      tbl = Table(
          {"a": ["", "a", None, "b"], "b": [4, 3, 2, 1]}, index="a"
      )
      assert tbl.get_index() == "a"
  
imports: import sys
  from datetime import date, datetime
  from perspective.core.exception import PerspectiveError
  from perspective.table import Table
  from perspective.table._state import _PerspectiveStateManager
  from perspective.table.libpsppy import PerspectiveCppError, t_filter_op
  from pytest import raises
label_desc: Use image node_id 49 for calling the TestTable obj's underlying member method code with example usage: obj.test_table_get_index() without return types