code: def testLoadNsynth(self, batch_size, sample_length):
      with tf.Graph().as_default():
          net = fastgen.load_nsynth(
              batch_size=batch_size, sample_length=sample_length
          )
          encodings_length = int(sample_length / 512)
          self.assertEqual(net["X"].shape, (batch_size, sample_length))
          self.assertEqual(
              net["encoding"].shape, (batch_size, encodings_length, 16)
          )
          self.assertEqual(
              net["predictions"].shape,
              (batch_size * sample_length, 256),
          )
  
file_path: magenta/magenta/models/nsynth/wavenet/fastgen_test.py
imports: import os
  from absl.testing import parameterized
  import librosa
  from magenta.models.nsynth.wavenet import fastgen
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 2 for calling the FastegenTest obj's underlying member method code with example usage: obj.testLoadNsynth(batch_size, sample_length) without return types