code: def json_serializer():
      return JSONSerializer()
  
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 23 for calling a global function with example usage: json_serializer() and returns: JSONSerializer