docs: def validate_examples(example_file):
      """Validate that examples are well formed.
  
      Pi should sum to 1.0
      value should be {-1,1}
  
      Usage:
          validate_examples("../data/300.tfrecord.zz")
      """
  
      def test_example(raw):
          example = tf.train.Example()
          example.ParseFromString(raw)
  
          pi = np.frombuffer(example.features.feature['pi'].bytes_list.value[0], np.float32)
          value = example.features.feature['outcome'].float_list.value[0]
          assert abs(pi.sum() - 1) < 1e-4, pi.sum()
          assert value in (-1, 1), value
  
      opts = tf.python_io.TFRecordOptions(tf.python_io.TFRecordCompressionType.ZLIB)
      for record in tqdm(tf.python_io.tf_record_iterator(example_file, opts)):
          test_example(record)