code: def test_numpy(self):
      with tempfile.TemporaryDirectory() as f:
          self.run_write_read_test(
              os.path.join(f, "test.npz"),
              NumpySerializer,
              {},
              {},
              {},
              {"shuffle": False},
              "Skip test_numpy, no numpy available",
          )
  
file_path: tensorpack/tensorpack/dataflow/serialize_test.py
imports: import tempfile
  import numpy
  import os
  import unittest
  from tensorpack.dataflow import HDF5Serializer, LMDBSerializer, NumpySerializer, TFRecordSerializer
  from tensorpack.dataflow.base import DataFlow
label_desc: Use image node_id 4 for calling the SerializerTest obj's underlying member method code with example usage: obj.test_numpy() without return types