code: def test_open_file_existent_file(self):
      number_of_lines_in_file = 30
      with utils.open_file(datapath("testcorpus.mm")) as infile:
          self.assertEqual(
              sum(1 for _ in infile), number_of_lines_in_file
          )
  
imports: import logging
  import unittest
  import numpy
  from gensim import utils
  from gensim.test.utils import datapath, get_tmpfile
label_desc: Use image node_id 2 for calling the TestUtils obj's underlying member method code with example usage: obj.test_open_file_existent_file() without return types