class_docstr: test write_VectorTransform using IOWriter Pointer
  and read_VectorTransform using file name
code: def test_read_vector_transform(self):
      d, n = 32, 1000
      x = np.random.uniform(size=(n, d)).astype("float32")
      quantizer = faiss.IndexFlatL2(d)
      index = faiss.IndexIVFSpectralHash(quantizer, d, n, 8, 1.0)
      index.train(x)
      index.add(x)
      fd, fname = tempfile.mkstemp()
      os.close(fd)
      try:
          faiss.write_VectorTransform(index.vt, fname)
  
          reader = faiss.FileIOReader(fname)
          vt = faiss.read_VectorTransform(reader)
          del reader
  
          assert vt.d_in == index.vt.d_in
          assert vt.d_out == index.vt.d_out
          assert vt.is_trained
      finally:
          if os.path.exists(fname):
              os.unlink(fname)
  
imports: import numpy
  import unittest
  import faiss
  import tempfile
  import os
  import io
  import sys
  import pickle
  from multiprocessing.pool import ThreadPool
label_desc: Use image node_id 2 for calling the Test_IO_VectorTransform obj's underlying member method code with example usage: obj.test_read_vector_transform() without return types