docs: def make_tf_example(features, pi, value):
      """
      Args:
          features: [N, N, FEATURE_DIM] nparray of uint8
          pi: [N * N + 1] nparray of float32
          value: float
      """
      return tf.train.Example(features=tf.train.Features(feature={
          'x': tf.train.Feature(
              bytes_list=tf.train.BytesList(
                  value=[features.tostring()])),
          'pi': tf.train.Feature(
              bytes_list=tf.train.BytesList(
                  value=[pi.tostring()])),
          'outcome': tf.train.Feature(
              float_list=tf.train.FloatList(
                  value=[value]))}))