code: def test_add_points(self):
      self.assertEqual(
          0, nmslib.addDataPoint(self.index, 1000, "string1")
      )
      self.assertEqual(
          1, nmslib.addDataPoint(self.index, 1001, "string2")
      )
  
imports: import unittest
  import numpy.testing
  import os
  import numpy
  import nmslib
label_desc: Use image node_id 2 for calling the StringTests2 obj's underlying member method code with example usage: obj.test_add_points() without return types