code: def test_transformer_pickle_unpickle():
      seed = np.random.RandomState(42)
  
      x1 = seed.normal(0, 100, (1000, 50))
      x2 = seed.normal(0, 100, (1000, 50))
  
      index1 = PyNNDescentTransformer(n_neighbors=10).fit(x1)
      result1 = index1.transform(x2)
  
      mem_temp = io.BytesIO()
      pickle.dump(index1, mem_temp)
      mem_temp.seek(0)
      index2 = pickle.load(mem_temp)
  
      result2 = index2.transform(x2)
  
      np.testing.assert_equal(result1.indices, result2.indices)
      np.testing.assert_equal(result1.data, result2.data)
  
imports: import os
  import io
  import re
  import pytest
  from contextlib import redirect_stdout
  import numpy
  from sklearn.neighbors import KDTree
  from sklearn.neighbors import NearestNeighbors
  from sklearn.preprocessing import normalize
  import pickle
  import joblib
  import scipy
  from pynndescent import NNDescent, PyNNDescentTransformer
label_desc: Use image node_id 21 for calling a global function with example usage: test_transformer_pickle_unpickle() without return types