code: def test_csv_serializer_list_of_list(csv_serializer):
      result = csv_serializer.serialize([[1, 2, 3], [3, 4, 5]])
  
      assert result == "1,2,3\n3,4,5"
  
imports: from __future__ import absolute_import
  import io
  import json
  import os
  import numpy
  import pytest
  import scipy.sparse
  from sagemaker.serializers import CSVSerializer, NumpySerializer, JSONSerializer, IdentitySerializer, SparseMatrixSerializer, JSONLinesSerializer, LibSVMSerializer, DataSerializer
  from tests.unit import DATA_DIR
label_desc: Use image node_id 7 for calling a global function with example usage: test_csv_serializer_list_of_list(csv_serializer) without return types