code: def test_should_return_correct_length(self):
      batch = Batch(create_dataframe(5))
      self.assertEqual(5, len(batch))
  
imports: import unittest
  from test.util import create_dataframe, create_dataframe_same
  import numpy
  import pandas
  from evadb.models.storage.batch import Batch
  from evadb.parser.alias import Alias
label_desc: Use image node_id 18 for calling the BatchTest obj's underlying member method code with example usage: obj.test_should_return_correct_length() without return types