code: def test_batch_delete_extra(self):
      index_store = IndexStore()
      self.assertEqual(index_store.getidx("a"), 0)
      self.assertEqual(index_store.getidx("b"), 1)
      self.assertEqual(index_store.getidx("c"), 2)
      self.assertEqual(index_store.getidx("d"), 3)
      self.assertEqual(index_store.getidx("e"), 4)
      self.assertEqual(index_store.getidx("f"), 5)
      del_idxstore = index_store.batch_delete_vals(["b", "e"])
      self.assertEqual(
          list(del_idxstore.items()),
          [(0, "a"), (1, "c"), (2, "d"), (3, "f")],
      )
  
      del_idxstore2 = del_idxstore.batch_delete_vals([])
      self.assertEqual(
          list(del_idxstore.items()), list(del_idxstore2.items())
      )
  
file_path: scattertext/scattertext/test/test_indexStore.py
imports: from unittest import TestCase
  from scattertext.indexstore.IndexStore import IndexStore
label_desc: Use image node_id 5 for calling the TestIndexStore obj's underlying member method code with example usage: obj.test_batch_delete_extra() without return types