code: def test_check_header_6(self):
      path = os.path.join(test_dir_path, "test_datasets")
      a_dataset = "sample_table_small.csv"
      with io.open(
          os.path.expanduser(os.path.join(path, a_dataset)),
          encoding="utf8",
      ) as f:
          header = next(unicode_csv_reader(f))
      self.assertEqual(header, ["id", "left_a", "right_a", "label"])
      header.pop(1)
      id_attr = "id"
      label_attr = "label"
      left_prefix = "left"
      right_prefix = "right"
      _check_header(
          header, id_attr, left_prefix, right_prefix, label_attr, []
      )
  
imports: import io
  import os
  import shutil
  import unittest
  from test import test_dir_path
  from nose.tools import *
  from deepmatcher.data.field import FastText
  from deepmatcher.data.process import _check_header, _make_fields, process, process_unlabeled
  from torchtext.utils import unicode_csv_reader
  from deepmatcher import MatchingModel
  from urllib.parse import urljoin
  from urllib.request import pathname2url
label_desc: Use image node_id 5 for calling the CheckHeaderTestCases obj's underlying member method code with example usage: obj.test_check_header_6() without return types